Not a stupid question at all — it's the #1 concern people have before switching.

Short answer: most banking apps work fine on GrapheneOS if you install Google Play Services via the sandboxed Google Play compatibility layer (it's a built-in feature, not a hack). The key difference is that Google Play runs in a sandbox with no special privileges, unlike stock Android where it has deep system access.

What works:
- Most banking apps (Chase, Revolut, Wise, etc.)
- Payment apps (Google Pay does NOT work, but most others do)
- Work apps (Slack, Teams, Outlook — all fine)

What might break:
- Apps that check for an unlocked bootloader (some banking apps do this via Play Integrity API). GrapheneOS passes basic integrity checks but may fail strong/device integrity.
- Google Pay / tap-to-pay (requires hardware-level attestation)
- A few rare apps that specifically block custom ROMs

Pro tip: Before wiping your phone, check the GrapheneOS community's app compatibility list. And you can always set up a separate "work" profile with sandboxed Google Play while keeping your main profile Google-free.

It's way more compatible than most people expect.