Instead of overlaying its own UI on top of form fields, I'd like Bitwarden (or any other PW manager) to act as a provider for the underlying system's native fill service, usually the browser, or Android, or OSX. They will always work much better than any 3rd party app.

Is that possible, does that exist?

I think they do that on Android but also have the accessibility based option.

I use it on Android and it's always been a Bitwarden-specific pop-up that shows up on password fields. Maybe with accessibility mode it would work as you mention? Ok that's a new thing to test.

I assumed that the accessibility one is non-standard and Bitwarden's uses the system native one. Because I see Bitwarden in passwords and autofill in settings (or something along those lines). I find it to work way better than on iOS anyway.

I don't think that the visual indication means they aren't using the system way. The accessibility service is probably not a good idea given how much control it can give the app over your system.

They do that on iOS. Integrates quite well.

Just to clarify, you mean something like it is done in iOs?

Probably! I just haven't seen it working on iOS. I'm mostly on Android, Windows, Linux, and Firefox everywhere.