does anybody know where to find the laws regarding footpaths?
In our settlement there is a wide footpath designed to allow emergency services (ambulances, firefighters trucks) to comfortably come in and do what they need to do - the nearby houses would be unreachable otherwise.
The path is otherwise classified as a foot/bike path open to the public even though it's owned privately by our settlement.
What I'd like to understand is: from a legal perspective, can residents, contractors and relocation companies use it temporarily to load/unload their cars and vans? Or is that illegal?
I see plenty of cars/vans/trucks temporarily parked on sidewalks everywhere as they obviously have a temporary reason being there. As such, I'm guessing there is some flexibility, but I'd like to understand if it's simply pragmatic lasseiz-faire or actual flexibility somewhere in the civil/transportation code.
Since it is private ground there is only a problem if the owner of the ground makes a problem of it.
As for governmental/city owned sidewalks it is very simple, this is legally prohibited unless specifically allowed. (Think of a daily license for a moving company)
You're leaving out the possibility of a "Servitut". That's an entry in the real estate registry ("Grundbuch") that requires the owner to do or allow or provide certain things. In this case (in all likelihood) at least one Servitut is in place, namely to grant passage to the public. That should make any issues (potentially) a public matter.
OP, you can't stop or park deliberately where you block or seriously hinder the other traffic. An access way for firefighter trucks must be at least 3.5m wide where it's straight, so parking a delivery van or truck to unload should leave enough room for the pedestrians, pram pushers, bikers, and skateboarders, especially when there's a grass strip to (partially) park the truck/van on.
So, as long as the driver is close by and easily spottable in case of an actual emergency, people probably won't bat an eye.
In the absence of parking areas or other explicit permission, parking motorised vehicles on sidewalks is forbidden, AFAIK always and everywhere. The fine you get depends on the remaining free width, and on the time parked if the free sidewalk is more than 1.5m wide, but it's forbidden anyway. Parking scooters, motorbikes, etc is usually tolerated if the remaining free sidewalk is at least 1.5m wide.