Did a minimal install of Arch Linux on the Surface Go 4, plus GNOME and Firefox, Tailscale and Sublime Text - everything worked, even the touch screen. Wi-Fi, Bluetooth, audio, all supported & no config needed. The only thing I had to change was to disable auto screen brightness and dimming, as it was changing way too rapidly (I dislike auto brightness on a PC anyways, I usually disable it). Idle RAM usage with Firefox and a few tabs is around 2.5GB-3GB. Not bad. Very usable.

Still tempted to chuck Windows back on, but use the Enterprise LTSC version. Wonder what the RAM usage would be, hmm.