Steam Deck is OK. Probably too expensive if you're not gonna play it as a portable ever, but not awful. The desktop experience is a jank-fest (the usual amount of Linux desktop jank, plus a whole pile more for some reason) but it's pretty good, actually, as long as you avoid desktop mode and stay in the Steam experience as much as possible.

It is too underpowered to do much gaming at 1080p (let alone 4k) except older games, but handles its native ~720p pretty well. You have to go into desktop mode to get higher res than that (on an external monitor), but you'll only want to do that for games that are both older (so that it can run them at tolerable frame rates at 1080p) and that really need the extra pixels, anyway. The Proton stuff works quite well, most things that run well on modern Windows in widescreen without a bunch of hand-ini-editing config tweaks or whatever work fine on the Steam Deck without much pain.

Decent option if you catch it on sale. Depends on what you play, though. Some folks find its mouse emulation touchpad thingy decent, but I found it a fun-killing chore for any kind of pointy-clicky-draggy games (Paradox, various tactical war games). But, you can play those games docked with keyboard & mouse and they're ok.

It's a hell of an emulation system for older console games....