>>283439717
OBS, either pointing at the game mirror window, or with the openVR input plugin to capture more vertical FoV. You can set up a hotkey to toggle on/off recording with openvr advanced settings, or just use the overlay. I like XSOverlay, but the native steam one is fine too.

OBS also has a shadowplay-like replay buffer that I've been meaning to set up, but haven't got around to it yet