Compatibility is always touted as the primary reason why Windows trumps Linux for PC handheld gaming, but I'd say that the Steam Deck is probably more compatible with the types of games that I play than handhelds like the ROG Ally. Sure, more games may run outright on the Ally, but how many of those are genuinely playable if they rely on a mouse for control? These are supposed to be handheld PCs but for most of them you'd need to plug an external mouse in and sit at a desk to get the most out of a large number of PC games. Touchscreen control is often awkward at best for management games and games with similar mouse-driven interfaces.

I think the Lenovo handheld has a touchpad from the looks of a few photos, so at least they've understood the problem. If you play the sort of games where you'd mostly use a controller anyway you've got a lot of good handhelds to choose from. If your game library looks a lot like mine though, your choice is limited.