My phone is as Degoogled as I could get it with Lineage, & I don’t use any banking apps on mobile, so I can’t give too much info there. For 2 factor Auth Apps, I use the Proton one and it works a treat!

Edit: Blerg!!! I have been having issues with the Proton Authenticator, You need Gapps or MicroG to get it to work properly.

Edit 2: Aegis works