Back in 2015 there was a guy outside Globus in Basel who had a stand selling British style short crust pastry pies, he told me he got into pies when he worked for Jamie Oliver for a bit. They now sell them in the food hall.
Quite a few chicken trucks in Zürich Unterland, usually just one day in the week in each location.
Over the German border in Hohentengen am Hochrhein there is a truck on Thursdays with chicken and Schweinhaxe on the main street almost in the middle of the village; @ half the Swiss prices.
Ah yeah, that's Markplatz. All kinds of goodies to be found there on a good day.
In Zürich:
1) Kreuzplatz has a Güggeli truck/stall every Wednesday. Well-seasoned if quite salty. The garlic sauce is on point, imho.
2) Porchetta is on the daily lunch menu at MAME in Seefeld, a café best known for its artisanal roasts (co-founded/owned by a repeated top scorer at the World Barista Championship).
These Güügeli stands can make a lot of money if franchise owners take their business seriously and are located in a good spot.