I don’t quite understand the criticism. It’s not gonna be top of the line, but it’s more than enough to replace my dying laptop from 2015 that I pretty much only ever use like a desktop anyway. And I can save myself the time and effort of picking parts, building, and dealing with shit not working as expected.
There’s a project that persists non-flatpack software, though it might screw up if it changes something that Valve updates: https://github.com/Chloe-ko/SteamDeckPersistentRootFs
A more reliable method would be installing them in distrobox. It’s kinda like a VM, but it uses the same kernel so it’s not much slower.