I'm not quite the person you originally asked, but I've also got a Steam Deck, maybe I can help? Full disclosure, I primary use my steam deck as hand held (switch killer), so I can only kind of speak the big picture performance, but I really like my steam deck. It's probably my new favorite way to kill time while traveling (assuming I can keep it charged or find somewhere to plug it in). Under the hood it's a remarkably capable computer, but it does have limitations, so I hesitate recommend it for everyone. It really depends on what you plan to play on it and your expectations. Its handled pretty much every game I've thrown at it (Hallow Knight, Lego Harry Potter, Slay the Spire, Ara Fell, Baba is You, Vampire Survivors, Spiritfarer, Shattered Pixel Dungeon, and West of Loathing) very well, but I've mostly stuck to verified titles from my library of mostly indy games. That said, it can be quirky sometimes. It's hard to explain beyond just general Linux weirdness, but it's stuff like the mod manager for Slay the Spire being fully functional, except for the part where you can't see it (if I recall correctly it only draws when java redraws the window, like when a touch is registered), but after the modded game is launched, it runs perfectly fine. I have also heard that the steam deck can struggle a bit with more demanding games, especially on higher settings.

If you're looking to get 4K 60+ fps max settings on the latest AAA title, I'd probably steer you towards a custom build, but if you aren't looking to push those kind of frames and are okay with some occasional software tinkering, then it's hard to go wrong with the steam deck.