At launch, it was cheaper than other PC handhelds

Still is.

and had better performance

I mean that's a virtue. All the other consoles used to have better performance as well. The only way it could compete with the latest tech is to release a new one with higher performance, which is not what you want. You want devs to have stable performance targets.

And while SteamOS was buggy

It hasn't gotten worse...?

the UI was much better to navigate than Windows.

...still is. As would a Steam console.

As for a console that game play PC games, there’s just more competition and and less unsolved problems to solve.

There's zero competition, as far as I can tell...