Is it possible that e.g. banking apps can technically detect that a not Google certified operating system is in use or can read system resources such that the operating system has been modified?

If this is the case, I am afraid that banks will refuse warranty claims (e.g. if the bank account has been hacked, etc.) if their applications are used on an operating system that does not comply with their terms and conditions.

    sh4tr0x
    Apps can use the Play Integrity API to check if the OS is Google-certified or not, which is more likely to be used to simply stop users from using the app in the first place. I find it unlikely that they will allow the use of their apps on an unsupported system, just to turn around and start denying/refusing certain stuff. Doesn't really make sense to me.