Honestly, I’m not clear whether Aurora differs from Bazzite in a way that affects this, and I wouldn’t have expected them to be different. Everything I’ve seen indicates you generally can’t mount a traditional filesystem from a systemd user unit. It’s not “unit files” in general, it’s specifically .mount units: mounting typically requires elevated privileges which user services don’t have by default. For most filesystems, the normal pattern is to mount via a system-level unit (or another privileged mechanism) and then control user access via ownership/permissions (and, where applicable, mount options). Maybe somebody else will respond with more info. Its weird that it worked in Bazzite.