Yeah non-upgradable 8GB VRAM would make it a no-go for all but the most casual gamers. But then the casual gamers would rather buy a PS5 for the same price, so let's see where this one fits in.
PS5 is too expensive long term and is not usable for anything else. And when Steam Machine becomes obsolete, I'll probably just use it/gift it as a mini pc/home-server to someone in the family.
And for that, assuming a reasonable price, it looks like a nice attempt. Certainly much better than last time.
For casual games even the steam deck can run most of them at 4k 60fps
If this little box is roughly PS5 power and reasonably priced (we shall see) then that might hit just right.