Just making it pass. Google advertises it as a way to find out if a device is secure with a locked bootloader and enforcing SELinux, but it's really just checking if it looks official. Finding a way to get through the checks is what lets you use your banking app on a custom ROM.

Do you work on all levels or just BASIC_INTEGRITY? (I understand that's already a ton of work, but increasingly I find banking apps need more even for basic functionality).