As mention Viktor, the usage of Proton Pass is misleading because the password is saved in a clear way in the clipboard.
Some keyboards are a nightmare because they do no have a timer to make the copied value expiring and force to cleanup manually. This should be an option we can tune (by example forget after paste or expire after 1 minute). As Microsoft keyboard, an option should allow to not learn what we are type and show in proposal bar some passwords we typed manually.
I have still not tested FUTO (marked as alpha), but clearly it make sense for me to have a keyboard with Proton Pass.

Try FUTO

iOS needs this because there's no GBoard alternative for bilingual users

FUTO Keyboard is already a great alternative to default keyboards
Proton should focus on developing and improving existing products such as autofill in Pass rather than figure out a whole new system of how keyboards work with the Android system and the thousands of apps they are used on

have you tried FUTO keyboard?

Also we cannot be private if Google , Samsung, Microsoft, etc keylogs everything we type. we need a safe keyboard/clipboard manager
Especially integrated with proton pass and proton authenticator (they btw should be one app)

Use GrapheneOS

For what it's worth, on Android I use AnySoftKeyboard. It's completely offline and integrates very well with Proton Pass.
It has offline swipe and autocorrect, along with theming options and more tweaks than you know you want. I highly recommend.

Also those virtual keyboard apps submit user data. My hairs stand up when I think about that people type their password using these apps.

A Proton Keyboard would be nice especially if it tightly connects to Proton Pass.