Listen, I would pay good money for an off the shelf console first computer that runs SteamOS, has as primary input a controller and an ARM architecture or any other small form factor x86, that fits under the TV. Freaking SteamMachines were a top notch idea, and Gabe should go for it again.
That gets wildly different with how taxing games are and how much they specifically take advantage of x86_64 instructions sets. Even decade old games would barely squeak by, if they don't break entirely.
I think it's worth checking out some diy alternatives that get the job done. I built my own "steam box" with some cheap Ali Express parts (Elsa 5700xt and Erying motherboard with core I9 equivalent engineering sample) to great success. The OS is key. I've found two that work very well:
Would love a new Steam Machine and could actually be good this time. Proton didn't exist when they released the original Steam Machines which limited you to linux ports of games. I had bought two but wiped & did clean installs of Windows 7 so we could play all the games wanted to.
Before Proton, gaming on linux relied on native ports or WINE. Native ports were rare & not always better. WINE took some learning to make work well but I dunno, never got any good at it.
I have a suspicion that they are making something. In an interview about the steam deck refresh one of the engineers mentioned how they couldn't find an AMD apu that was efficient and powerful enough to warrant making a steam deck 2, he said not in this chassis anyway. Insinuating they know of one for a different chassis. Pinch of salt.
The OS was also very limited with focus on Linux ports of games which there were not very many at the time. Proton wasn't a thing yet. I bought two of them, one for myself and one for my brother. I tested it out & it was neat but wiped both to do clean installs of Windows 7 so could play the games we wanted.