But we don't have anything like FF as an alternative to go from Android. Especially considering banks require "certified OS".
https://grapheneos.org/releases
(Pixels only)
Go for Calyx or any other android distro, they have zero difficulties in supporting more devices.
Personally, I wish there was an open/libre device on the market that GrapheneOS could target.
You mean, Pinephone and Librem 5?
Also: Android. If I didn't need Android/iOS apps, I'd be using a Nokia 3210.