Basis of my commentary: I'm a Swiss native and live in Glattpark (have done for almost ten years), my parents are British and Swiss French respectively.
The school thing: this is probably me being very, VERY Swiss but I grew up with the mindset that only kids who had something wrong with them needed to go to private school. With the challenges of increasingly diverse classes (I don't just mean in terms of nationality!) and not everyone handling that quite so well, this is probably no longer a fair view to hold, however, the standard of Swiss public schools is pretty high. If your kids are fairly neurotypical and you have long-term plans to stay here, they will be perfectly fine there.
Just don't have a fit when they are allowed to use power drills in woodwork class in primary school, mkay? I still have all my extremities, it's fine. Your kids will definitely not be the only foreign-born kids in class, looking at the classmate list of the little girl who used to live downstairs, there were maybe three recognizably old-school Swiss names on there out of 16 children.
Not sure why you think they would be taught in anything other than German, mind, German is the local language. They do add French and English as they progress and there is some level of support for kids who do not speak German but you really are expected to learn fast and get integrated. By the way, neither of my parents are German native speakers, somehow they still managed.
The shopping thing: Departing from Glattpark it is 8 minutes on the tram to Zurich airport. Not sure if you are joking about access to the market and have simply not checked out the transport links but the 781 bus takes you from the Giebeleichstrasse stop to Oerlikon train station in ten minutes. There is another bus that goes along Schaffhauserstrasse via Seebach into Oerlikon. The number 10 tram takes you there from Glattbrugg station, Flughofstrasse or Lindberghplatz. Or you could take the train from Opfikon station. Summing up: It's ten to 15 minutes tops to get to Oerlikon, so setting up our own duplicate infrastructure would be totally redundant. The people of Opfikon-Glattbrugg mostly shop either in Oerlikon, Glattzentrum or the Airport. Direct public transport to all of those is available, although I usually just cycle there.
Mind you, there are some pretty good farm shops available according to a mate who has lived here all his life, it's just that I never sought them out, they are in the "original" part of town. The shops in Glattpark are well stocked and we recently even got a Turkish market that is now open until 10 pm, they have good fruit and veg as well as a large selection of ingredients that go beyond Turkish cuisine, such as a whole shelf of Indian stuff.
Noise: I can't say that without knowing which part of Opfikon we are talking about. However, there is a wealth of information on this on the airport website. Obviously, anywhere that is under the flight path will be noisy every once in a while. The weather can change this completely but the regime is usually as follows: Mornings and evenings they tend to land over Opfikon, around lunch they take off and that can be pretty loud. For example, if you are in the Oberhauserstrasse area, you will briefly have to interrupt your conversation if a plane is taking off. Ditto for houses that are between Fabrikstrasse and the motorway.
Appearances: If you want pretty, a short commute into Zurich city, good schools, good quality of life, not to be one of the rare foreigners in the location AND room for future kids, you will need to increase your budget. By a lot. Küsnacht may be more your speed, or Kilchberg/Thalwil. You admit to it possibly sounding snobbish, I would say that this is clearly your first rodeo in the greater Zurich area housing market.
Opfikon-Glattbrugg is one of those places whose proximity to Zurich and a large international airport had a small and picturesque farm village receive numerous additions over the years, not all of which terribly well thought out, I agree. The proximity to the airport and (at the time of construction), relatively affordable price of land made it interesting for companies to plonk offices and warehouses on. A lot of stuff has already been replaced/refurbished but there doesn't seem to be any cohesive plan. The Glattalbahn only started going there a little over ten years ago, so it wasn't quite as well-connected before that. In a way, it is still catching up and trying to figure out what it wants to be. I think Wallisellen and Dübendorf have more of a concrete plan in that regard.
But what I can tell you for certain: The tax rate and cost of health insurance is lower than it is in Zurich. By a lot.
Rather than aesthetics, I would maybe think about safety or what opportunities you have to enjoy your free time. For example, there is a fantastic newly renovated swimming pool - indoor and outdoor. The Glatt river is lovely for walks and the forest on the hill contains a vita parcours if you want to keep fit in the fresh air. There are quite a number of crèches from what I gather, the local associations are very active and I see kids actually playing outside on their own, so it must be safe enough.
Another bonus - no need to join the insane Saturday queue at Hagenholz if you need to dispose of something, we have our own recycling place that has a thrift store attached to it. If they think whatever you want to get rid of can be sold to someone else, you can just leave it there rather than having to pay for its disposal.
Being right in between the airport and the city means that you have more emergency services available for call out than in other places. For example, the local volunteer fire brigade has a whole hangar full of equipment including a 32 metre turntable ladder and pretty much every other gizmo you could possibly want.
Fibre internet: I just can't with this level of first world need... The internet works ok for my HD quality streaming and the numerous video conference calls I've had these past few months, that's all I can say about that. According to this map , we already have it in most parts of town but it appears that you have different information. That map can also give you information on a whole host of other things such as noise from roads/rail.
My top tip would be: unless you are buying a new build that is yet to be built, don't spend too much time wondering about your favourite series being downloaded in 0.5 seconds or what have you because good places go fast. This may not be quite so acute in the current environment but who knows, when freedom of movement first started to be a thing back in 2005, it only took five years for house prices to go up by about 30% in Zurich. One place I looked at back in 2009 was on the market for 750k but had been bought for 325k in 2005. And the real estate agent refused to send me a floor plan because "the price is going to be higher than advertised and we already have 20 people wanting to make a firm offer". It didn't even have its own washing machine or a proper balcony! Since the freedom of movement will continue and Switzerland remains very attractive to highly-skilled foreign workers who place more of an emphasis on owning their home than many Swiss people do, combined with real estate investment being an important way for pension funds to make money since interest rates are kerplunk, there is a lot of competition.
By the sounds of it you are still a bit focused on the nice to have rather than the must have part of the search. I realise that buying a home is a big deal and yet, with the very small number of places available and your presumably "normal" budget restraints, you need to stop being too much of a Goldilocks if you really want to end up with a home to call your own. Location is certainly key, as you cannot change that. But the fibre optic thing is just... amusing.