Will studios focus on the RTX 6090 or give slower machines a chance?

Any studios that make games that require an RTX 6090 aren't worth your time or money. These studios tend to make unoptimized slop.

Also, both the RTX 4090 and 5090 are notorious for catching on fire, despite being horribly expensive. Don't waste your money on 90-class cards.

They cared enough for the Deck.
So probably?

All depends on the sales numbers. Since the Steam Deck and Steam Machine both use Linux it gets more and more interesting.

I think what people are forgetting that steam machine is literally a PC. It’s not a console to port something onto it. As long as the game supports proton it runs on it

I mean yes and no. We've already seen AAA devs giving attention to the much less powerful Steam Deck. Many of them going so far as to include a graphics preset for it. That's part of the point of Steam hardware, to give devs a popular and standard hardware target for development.

Will all of them? No.

Some devs already target Steam Deck verified compatibility. Any attention to the Steam Deck helps the Steam Machine too, you'd just be playing the game in higher resolution and higher frame rate. The combined market may be more appealing to devs, but I don't see the Steam Machine selling enough to make a major difference here.

Are the Steam Machine's components good enough to run PS5 ports?

Yes, it's only slightly weaker than PS5, it's much more powerful than Steam Deck

Depends on how much it sells. The Steam Deck has had an impact, the Steam Machine will also be targeted if it sells.

A good amount of devs cared about the PS Vita and a good amount care for getting a Steam Deck verified badge. If the Machine can pull off another 5-10 million Linux user, not bad. Not many studios focus on the RTX 4090/5090. The most popular console of the last decade was the first Switch. PC emulation on Android as it matures may be a bigger target someday to attract sales for developers

Some will no doubt. There will be some that don't.