I don't think anybody's sanctioning the use of driver assist features on small twisty roads the snow yet, are they? If so please share what you were driving - that would be interesting even if it didn't work well at the time. Most of these things, AFAIK, are in the LKAS, ACC, LDW range and meant for highways and there are mutterings about that in the manual. I sometimes use ACC and/or LKAS on country roads but only with very low expectations.

Teslas at least get better over time. If it got confused over a fork in the road, there's a decent chance that after a near-future firmware update that same car will no longer be confused. A few folks have acknowledged that they're now smart enough to slow down for curves (even sometimes a bit generously), and they are among the few that work pretty well off-highway (most of the time).