This was back in 2011. We modified the init script to stop the zygote process from launching, then used our own C code running as a normal Linux process to work

This was back in 2011. We modified the init script to stop the zygote process from launching, then used our own C code running as a normal Linux process to work with /dev/fb. So yeah it was rooted and it was an old version, but we were mostly outside of the Android ecosystem entirely.