FWIW I've got grapheneOS without google play services on a financial profile, and all of my financial apps work including: -Two credit card apps -Bank app -Three investing apps -Two direct transfer apps

One of the credit cards apps (amex) does give a "warning" on each page that it needs play services to function but if I click Ok it actually still just works.

Worth trying first. In my experience, almost every app works without the Google store. You can also block the internet access for any Google service or app via its settings.

The best middle ground is probably GrapheneOS with sandboxed Google Play Services. At that point, most things "just work" and you can at least mitigate Google's spyware.

In USA I've found it's pretty easy to live without banking on your phone, although you can't say the same for some other countries. Granted I have a job where I am working with my own desktop computers most of the day, so I can pay bills and transfer funds on them during those times - and lots of people might not have the same luxury. But I've yet to feel a need for any of them while out and about beyond a few occasions of Venmo'ing funds on the go - and at least Venmo still allows you to use their site via browser.

Fortunately those apps are not required (and dangerous to use anyway)