Personally, I would stick with the 19" options. It's not worth it IMO for 20" given the lack of tire options and costs associated with said options. If you need an all season you'll find many more options at lower prices for that fitment.
Also, should you ever have a blowout while traveling, you're FAR more likely to find a 19" replacement in a small town tire shop to get back on the road again. The ride quality is better, the efficiency is (slightly) better and the wheels cost less too. You also get a little bit more protection from curb rash and pothole damage although these differences are less than it would be to the 21" obviously.
As for other aftermarket wheel makers... not too many focusing on the Tesla cars specifically. You can find universal fitment aftermarket wheels but be VERY careful that they're rated for the weight of these cars as they can be quite a bit heavier than similar sedans that would normally fit that bolt pattern. Tsportline specs their wheels to handle the forces associated with our MUCH heavier and MUCH more powerful cars.
Personally, I went with the 19" Arachnid replicas because I dig the way they look, they're cheaper than lots of other options and I can select the Arachnid wheels for the car visualizations so your car looks closer to how it looks in RL in the display and app. Some may not care about that but having the visuals not match would dive me crazy beyond words.