An update on Swiss proprietary apps:
The current version of Swiss Map Mobile does not seem to work on Fairphone Open OS. I asked for support from Swisstopo but they will not offer any for a “non-official” version - i.e. an apk which didn’t come from Google Play. I had already paid to buy a licence to access the maps offline; all they offered was a reimbursement. I will spend some time looking for alternative map viewers (the online version recommended by Swisstopo is of little use when you are in the mountains and don’t have any cell coverage).
The current version of MeteoSwiss works fine.
The new SBB app worked at some point, but I never liked it. I have been using transportr (see How to get (almost) all trains and buses in Europe with Transportr (FOSS public transport app)) for a few days and think it is a good solution.
The Rega app doesn’t seem to work without Google services, which is a problem. Does anyone use similar apps (meant to call rescue services in case of an emergency, e.g. in the mountains, even when you do not have enough coverage to place a call)?