Coming from KeePass and KeeWeb I personally prefer dedicated desktop apps instead of browser plugins. Right now the Bitwarden dedicated desktop app is more familiar to me, but does not auto-fill credentials in either any browser or other app.
There is a feature request thread about this here.
I learned something here, I didn’t realize BW could run without an internet connection to the most current web vault. I’ll have to try that. If this is true then it means there’s a local / encrypted copy somewhere on the machine, and that should be back-up-able. No ?