This site has a crowd sourced list of apps that includes their compatibility on deGoogled Android devices.
Personally, I've had very few issues with apps not working, and banking/productivity apps haven't given me issues on CalyxOS, but your mileage may vary
I've been on Graphene for 2 years now, and all my banking apps (from 3 different countries, business and personal) work perfectly.
I used Calyx for a while, and everything worked there as well.
For most deGoogled OSs that allow to te-lock the bootloader, there should be no issues when using banking apps.
/e/OS it is degoogled but most of the "Google" applications have been replacedby great opensource alternatives or adapted. The app store still allows us to install apps from the playstore but anonymously.
Fair enough. I considered it. Their scanning of people's clouds shattered the illusion of privacy for me and I just couldn't. Probably far better than google, but I'm not sure I personally could class it as good.
The apps I need (bank and ID) work perfect, my device even passes safetynet. I get updates from Playstore via Aurora. Only thing I can't do is pay for apps.