Aug 21, 2020 - 4:43 PM
in reply to rsmall
In general, most shops and supermarkets in Switzerland are closed on Sundays. Your best option to go shopping on a Sunday would be the Geneva airport where retailers operate all year round. However I'm not too sure if you can find to a retailer that sells camping gas canister at the airport.
The Geneva Airport website has a list of shops that operate at the airport. You can find a link to Geneva Airport here: www.myswissalps.com/airports/geneva
If you are staying in a camping site with a supermarket on site, there is possibility that you can get a camping canister there. Otherwise, you can check out Decathlon, SportXX or Ochsner Sport which are open Monday to Saturday.
Hope that helps!