The OS is Linux based, but that's not important for a developer. As you saw, the 3rd party application platform is based on a custom Java VM, which is for security and stability reasons. Unlike some other phone systems like SymbianOS, running native code won't be an option, which is what prevents ScummVM or AGS being easily ported.
It's still a good platform for games though.
It's still a good platform for games though.