No other handhelds have adopted it most likely because the drivers aren’t updated for the latest chipsets, which means all efficiency goes out the window (no pun intended). Sure you could probably run the updated Ryzen graphics on SteamOS but it probably wouldn’t benefit the hardware as much as Windows would, considering most power efficiency on Windows is handled more by the OS and not the chipset drivers.

Ayaneo already started taking preorders on a SteamOS based handheld, in addition to working on their own distro of Linux