I have some experience with some of these apps:

• open food/beauty facts: both have a long way to go IMO. The ui is very janky and lots of things don’t work. Open food facts seems to be a bit better but not much
• loop habit tracker: fantastic app, I use it every day, never saw a bug
• gadgetbridge: the ui seems rudimentary, but it has everything you need and it works really well. YMMV depending on which gadget you have though
• openscale: only used it for manual tracking. It’s very very basic but somehow I didn’t find a better alternative

I reported this bug here: https://codeberg.org/Bazsalanszky/Eternity/issues/234

Unless the app allows you to export/import your settings, unfortunately the answer is no.

This is because F-Droid builds its own installers and signs them with their own key. Android (sensibly) does not allow upgrading a package if the signing key is not the same.