But in the case of the mobile apps, downloaded from their respective platform's app store, how can you guarantee the code you see on github is the exact same code you're running on your device?
Admittedly this supply-chain-verification is an issue for all mobile app store apps but seems particularly important with something like a password manager.
For Google play store, there was also that developers needed to sign their apps before releasing to stores, so you knew that it came from developer, but Google removed that when they introduced app bundles. There is still a way to verify if the build is the same as developer provided, but automatic protections that were there are now gone [2]
[0] https://en.wikipedia.org/wiki/Reproducible_builds [1] https://mobileapp.bitwarden.com/fdroid/ [2] https://arstechnica.com/gadgets/2021/07/google-play-dumps-ap...
The page didn't mention anything about reproducible builds. (Doesn't mean they aren't using it though, but that would be internal.)
I haven't been willing to take it that far yet, though that appeals to me.