By default, though, a device with a custom ROM or root (basically anything but an unmodified stock ROM) will not have SafetyNet or Play Integrity API certifications. This means, apps that check for that (e.g. banking apps) won’t run on the device.
There is a tool (Universal SafetyNet Fix) which tries to fake these certifications and will give you full SafetyNet but only partial Play Integrity API status.
(Play Integrity API is split into MEETS_BASIC_INTEGRITY, MEETS_DEVICE_INTEGRITY and MEETS_STRONG_INTEGRITY. Depending on how lucky you are, you’ll get basic and/or device, but you will not get strong).
With Universal SafetyNet Fix I have yet to encounter an app that doesn’t run, but theoretically apps could be checking for MEETS_STRONG_INTEGRITY and then there is nothing you can do to get it running (short of modifying the app itself).
How does that work? Does it get Google play and everything on custom ROMs?
Usually yes, if you want it to.
By default, though, a device with a custom ROM or root (basically anything but an unmodified stock ROM) will not have SafetyNet or Play Integrity API certifications. This means, apps that check for that (e.g. banking apps) won’t run on the device.
There is a tool (Universal SafetyNet Fix) which tries to fake these certifications and will give you full SafetyNet but only partial Play Integrity API status.
(Play Integrity API is split into MEETS_BASIC_INTEGRITY, MEETS_DEVICE_INTEGRITY and MEETS_STRONG_INTEGRITY. Depending on how lucky you are, you’ll get basic and/or device, but you will not get strong).
With Universal SafetyNet Fix I have yet to encounter an app that doesn’t run, but theoretically apps could be checking for MEETS_STRONG_INTEGRITY and then there is nothing you can do to get it running (short of modifying the app itself).