One thing I see as underestimated is that having a major standard device is huge for indie development and could greatly benefit the most flourishing artistic landscape.
One of the problems today is that the indie and AAA markets are increasingly distant, publishing a game on the PS5 or XSX digital store is prohibitive for a small indie team, but if Steam Machine is successful, we can expect more easy access to indie games by (ex)console gamers, and later a reduction in publishing costs on consoles.
I believe Steam Deck has already started this process, but with a device that will compete with the 9th generation of home consoles the indie game diffusion could accelerate.
I was gonna say before reading your last sentence, the Steam Deck definitely could have accelerated this. It’s extremely accessible while doubling as a computer powerful enough for development. It’s pretty great they’re offering dev kits for the new Steam Frame, too. It’s really going to bust the scene wide open.