You can install Steam on almost any Linux device. The Steam Machine is great for those who want a portable console-like device. Have you ever tried to build and maintain a shuttle PC yourself? It's obnoxious. This makes the goal of high quality portable gaming much easier.
If you want a console I agree, it's expensive but you can leverage your existing library and use sales, so not too bad if you buy a lot of games.
The benefit of a SFF PC you made yourself it that it doesn’t use proprietary hardware like the Steam Machine, is easily repaired and easily upgraded.
Support says I need custom molds to reapply the liquid metal thermal compound, or it would 100% leak. Regular thermal compound just isn’t good enough. It was true. I could send it to China and they would fix it for free, but it would take 60 days and I would have to pay tariffs.
I just cut my losses and harvested the RAM and SSD for something more dependable.
Also, if his friends play Halo, CS2, Ark, War Thunder, Arma, Hell let Loose, Splitgate, TF2, DOTA, Overwatch, or The Finals, he'll be fine.