I’m slowly but surely switching everything I use to FOSS alternatives and after using Gboard for a while thanks to it’s good swipe typing, I moved to OpenBoard for the same reason. Unfortunately, the fact that I can’t auto-fill my password via 1Password is bugging me (on top of less-than-ideal autocorrect). You guys know any alternatives?
Keepass2Android provides both an autofill function and an alternative keyboard. As the name implies, it works with a Keepass file.
FlorisBoard is FOSS and behaves just like Gboard in regards to password auto-fill
You can also try AnySoftKeyboard as well, it works fine with Bitwarden. Also, it has many customization options.
I am using OpenBoard with bitwarden, and while it doesn’t offer the autofill in the autocomplete section it does work as a dropdown in the input field
I’m using GBoard on grapheneos with all permissions removed basically. Not quite what you asked for