Steam Deck vs. ASUS ROG Ally Arch Linux Gaming Performance
As some complementary data points, here are some metrics for the ROG Ally while still running Arch Linux but running at the native 1920 x 1080 resolution for these games rather than 1280 x 800 to match the Steam Deck.
The ASUS ROG Ally could run Counter-Strike: Global Offensive at around a 120 FPS average out-of-the-box or 160 FPS with the performance profile. As a reminder the ROG Ally has a 1080p 120Hz FreeSync display.
F1 22 with low quality settings had a tough time running above 60 FPS until putting the ROG Ally in the ACPI performance profile.
HITMAN 3 was also tough to run on the Z1 Extreme at 1080p. For these games it's likely better off running at a lower resolution and using AMD FSR or other upscaling tech to enjoy at 1080p.
Of course, the open-source games and other lighter-weight titles had little trouble running at high frame rates at 1080p with the AMS Ryzen Z1 Extreme.