Since it was released on the Switch 2 years ago, me and a friend have been playing online races pretty consistently.
Just now...have I discovered his Mii can keep his VR progress as well. How?
We needed to create a separate profile on my Switch, then he needed to create a Nintendo ID of his own. Once that was done, we launched the game & went into online on his profile. Logged back into mine, played a few games and points were being kept on the Mii/account he selected.
I can't believe they didn't make this clear. I'm sure we tried doing it in the past but we didn't end up creating a separate Nintendo ID...just the profile on my Switch.