How to add boot splash screen on boot?
theoretically you can change the splash screen on Raspbian/Debian/Ubuntu using the usual way. Splash screen configuration | Ubuntu
a more RPi specific utility does away with the heavy-weight plymouth daemon and uses a simple utility in the boot initfs. DarkElvenAngel / Initramfs Splash · GitLab
There should be a lot of information available for those using the CM3 module. The same ideas could be used on the A06 module, but I think this requires a fair amount of tinkering.