Software-wise, if you are using a Linux installation with KDE interface, on an AMD CPU and AMD GPU, and are using a wayland session with gamescope to play games, it is very VERY close to the Steam Deck and you are benefiting from all the optimizations that were made for Steam Deck. Bonus points if the hardware is Ryzen 3000 series and Radeon RX 6000 series.
You probably saw this, but Nexus Mods are asking feedback from Linux users, not just Steam Deck. Because, you know, apart from the sticks, size and touch pads, Steam Deck is just another Linux machine.