How different we think. I'd much rather put my trust in select people, such as Jason Donenfeld (creator of pass, Wireguard &c) with impeccable track records, than random companies that are always one quick change of management away from selling all your data off to the highest bidder.
I was rather alluring to the different mobile apps which all seems to often be developed by various unknown developers (some closed source) instead of the core developers of the main project.
I too would trust the core of e.g. Syncthing or pass.
Making it all work on mobile is a completely different story though. I myself can’t do without mobile access to my passwords.
The mobile platform is one I ignore. The only thing I know with any certainty about my phone is that it's running a bunch of closed source spyware, so I'm not entrusting it with anything much - and certainly not my passwords.