FOSS store required immediately

how much does mircrosoft have to do with steam beyond having an app? how could valve be made amenable to serviceing linux platforms in general, in addition to curating ported games? i know these guys were MS at one time but the past tense may be a benevolent condition.

https://en.wikipedia.org/wiki/Valve_Corporation

What other candidates for FOSS "store" exist beyond repositories? I dont think github is in that pool anymore.

if valve provided a linux onboarding platform, in addition to games and repos, that just may have beneficial consequences for FOSS and valve