Welcome!
Yes, I’m using F-Droid for my C2 and can’t use it for my FP4.
And I hope you will find a device that is fully supportens 
Android Apps won’t work (or even install) as community ports don’t have AAS (Android App Support). F-Droid is just a storefront for Android apps…
You may try Waydroid instead, there are some threads here if I remember right.
Thnx for the quick responses. Then I guess the best option for running Android apps on FP+Sailfish will be Waydroid. (Hopefully this will be possible after Waydroid moves to Android 14.)
One of the apps I’ll be missing is Proton Pass. It is open source, but only available for iOS and Android. Unless I’m wrong.