Yea, I thought the whole Lavabit episode made it clear that privacy oriented solutions based in the US were going to have a hard time. Most Proton’s whole selling point is their location.
And that they'll let you register even when connected to tor.
I tried and failed to get working account.
Huh, I though they did. But maybe I was wrong or they changed that.
I think they have a daily rate limit for free Tor accounts. You can make a paid account through Tor with Bitcoin, which of course you obtained by some anonymous method.