Forking and maintaining Linux does not take teams of people. I've been at it for > 10 years and maintained support for my 15 or so various SBCs/mobile devices, writing drivers, debugging, cleaning things up. It's a weekend project every 3 months + whatever you want to put in for development.
And there are others doing it for projects like Armbian, openwrt, etc.
And there are others doing it for projects like Armbian, openwrt, etc.