I think you're right. How about an EVSE with a 6-20 plug instead, along with a 6-20R to 10-30P adapter?
Here's an example adapter:
https://www.evseadapters.com/products/nema-6-20r-to-10-30p-adapter?variant=27441145032
Then for plugging into 120-volt, an adapter like this...