You're right, but it's slim pickings. I can't find a good place that has the option to select Model Y in any configuration. It's just too early I guess. The thing that sold me was both the ease of it all, and the fact that I really like how the wheel looks on a MY.
That all being said, what websites already allow you to shop by a Model Y car?
Tirerack.com and CarID.com
If you are shopping for new wheels and tires then you just need to look at the bolt pattern as the most important number which is 5x114.3 and offset +40 to +50 (stock is +45)
If you are buying wheels only and will use the stock tires then you should follow the spec of your stock wheels (19" or 20" x9.5)
I will be replacing my gemini wheels with this when I get mine MY
19x9.5 Inch Savini Black Di Forza BM15 Gloss Black (True Directional) (Concave) Wheels