This is the real secret of the Steam Deck's success. And it's something Valve has been working at for a decade now, starting with Steam Machines which completely failed. It's a strategic move to reduce their reliance on Microsoft and it must be great for them to see it succeed now after failing for many years.
I'm one of those people that has perpetually wanted to use linux as my main desktop, but inevitably find myself dual booting Windows for gaming, and then just making my desktop a Windows gaming box and then using a Macbook for dev work. I think I've had about 3 major runs of trying to be Linux desktop only, and that typically lasts just a month or two.
For the past year I've been using exclusively Linux (Pop!_os) as my desktop for everything I do, and that has involved quite a bit of gaming. It's really insane how giant a leap forward Proton (driven by the need for Steam Deck compatibility) is as far as Linux gaming goes. It does occasionally take a bit of tweaking to get things to work just right, but nothing too crazy.
It's also worth mentioning that, at least for me, System 76 has really solved the problem of "just open the box and turn it on" support for Linux. Extremely high build quality and most important, seamless support for Nvidia drivers. It is a blast to spend the day building deep learning models and then make use of that nice GPU to play AAA titles at max settings.
Any gamer who has been wanting to go full Linux Desktop for a while, it's really quite possible now.
My linux SSD is on its last legs though, and I've been planning to do a fresh install when I get a new one. I'm using Kubuntu currently but with all the headaches Snap has been giving me I think I'll give Pop!_os a try instead. Everybody that chimed in the other day on the thread about Ubuntu dropping Flatpak was raving about Pop!_os as a sensible alternative.
I just wish it didn't have such a silly name. :P