I think it could avoid some of the issues with gaming on linux because you could focus in on a unified platform and if there was a gaming SDK targeting the pi we might see orginal games being made as opposed to just ports.
Also what exactly would a micro-kernel entail? I'm much more familiar with game development than os development.
Most Raspberry Pi Linux distros take around 10 seconds to boot. It can be made faster by using a tiny distribution or something like https://www.linuxfromscratch.org/ but it would be nice to find an OS geared towards gaming.
What would be more interesting is an open source micro-kernel and gaming SDK targeting Raspberry Pi.
1. See https://www.pcgamingwiki.com/wiki/List_of_Linux_ARM_games