I'd say old fashioned Linux would come without any certification or support.

I didn't mean DIY / Linux from scratch.

and I meant where I come from a general purpose OS is for any purpose, not just to run it on a very specific stack.

SUSE - Find Certified Hardware Products https://www.suse.com/yesCertified/home

similar pages exist for RH and canonical

but then Windows also is a general purpose OS.

hm.

what if MS strategizes on their hyper-v as hypervisor, with windows as control Panel and all payload on their Azure Linux? popcorn time?