Ok, sea salt and balsamic vinegar crisps have been availble in CH for ages through Kettel Crisps (Jelmoli, Globus, St Annehof used to sell them too). But pricey...

As for going to the airport, what about Bahnhof Enge (big Migros) Bahnhof Stadelhofen (big Coop) and lets not forget Hauptbahnhof! But in general I think shops should be open on a sunday...