Not aiming this as Vestas but I am seeing so much misinformation, it's like people think the Steam Machine is an entirely separate thing that needs developing for, outside of current consoles/PC, I'm not sure why it's not clear that it's just a PC in a smaller box.
You aren't going to see, "Coming soon to PS5, XBOX, PC, Switch2 and Steam Machine".
It does actually need developing for.
Proton tweaks cover a lot on Steam Deck but they don't optimise every game & a lot (mainly indies/older stuff) simply don't work/are unplayable/crash (edit they work on SteamOS but not the deck).
I think I've returned about 8-10 games for refund as despite saying "Verified for Steam Deck" on the store page they simply didn't work in any sort of acceptable way. That's more games refunded in the last 3 years than in the previous 15 years.
Fortunately Steam are OK about this for most games.
The Steam Machine will (I expect) be the same as the Deck in that each game will have a slider to play at 30FPS/60FPS/unlimited FPS as people are going to use them on TVs. Again that requires developer input/design in order to work well.
Given the spec of the Steam Machine there's going to have to be a shedload of Proton optimisation going on to get things to play right - and there's limits to what they can do. For example it looks like Valve are going to try and get AMD to permit them to use "INT8" FSR4 on the RDNA3 graphics chipset - if anyone has actually seen this then you know some games look OK and some are totally screwed. INT8 FSR4 isn't anything any games developer is going to code for by default as its a bodge for an old/obsolete graphics chipset.
So yes in some respects its a PC - SteamOS/Arch Linux mean you can do all sorts from the desktop (like run old emulators), but in another respect its a console which requires games optimisation in order for games to run well on the hardware. People shouldn't necessarily conflate what SteamOS can do on decent hardware with what it can do on the Deck/Steam Machine.
In terms of pricing I said here (
https://forums.overclockers.co.uk/threads/steam-machine.19008233/page-2#post-38091060) that it'd be £850 for the base spec, £1k for the 2TB. I don't see any reason to change that estimate as you get a controller bundled in and they're likely to be the best part of £100 when sold alone. Valve say they're not willing to take a loss on the hardware, which given they take 30% of every sale on Steam might be seen as shortsighted....