It is fantastic to hear you're considering GrapheneOS for your device. Please if you have any questions at all reach out to me and I will be more than happy to provide any up to date information/answers that you might have, should the documentation on our site not cover it.
Just as an FYI...
GrapheneOS and CalyxOS are much different. GrapheneOS is a hardened OS with substantial privacy and security improvements:
https://grapheneos.org/features
CalyxOS is not a hardened OS. It substantially reduces security. It recently went 2 months not shipping standard security patches.
Compatibility with Android apps on GrapheneOS is also much different. GrapheneOS provides our sandboxed Google Play compatibility layer:
https://grapheneos.org/usage#sandboxed-google-play
Can run the vast majority of Play Store apps on GrapheneOS, but not CalyxOS with the problematic microG approach.
CalyxOS is closer to LineageOS they both share the same issue above and they both always use multiple Google services too while giving them privileged access even if users don't use microG. It would be wrong to imply they don't use Google services. microG is of course an implementation of Google services. GrapheneOS doesn't use Google services by default.
To clarify further they always use Google services even without microG. They use Google for connectivity checks, network time, attestation key provisioning, SUPL, DNS fallback (LineageOS only), PSDS (Pixel 6 and 7), eSIM activation and more enabled by default.
https://blog.privacyguides.org/2022/04/21/grapheneos-or-calyxos/ is a 3rd party article explaining some of the substantial differences between GrapheneOS and CalyxOS. It's a common misconception that they're similar. CalyxOS is far more similar to LineageOS than GrapheneOS. There are many other alternate OSes available.
https://privsec.dev/posts/android/choosing-your-android-based-operating-system/ is another article about privacy and security differences between alternative Android-based operating systems.
PrivSec also have a community resource for banking apps that work on GrapheneOS that can be contributed too, make sure to check the issue tracker too for submissions that might not be on the list yet.
https://privsec.dev/posts/android/banking-applications-compatibility-with-grapheneos/