I was able to create an account on a paid Proton VPN, I think around…December or January. There’s no reason to suggest something has changed since February. I detailed the major changes in the OP, I’m unaware of anything that’s happened since Feb.
Email service, I think was simplelogin.
It happened after many attempts. I honestly don’t even know how it worked. I also changed up my browsers a few times, I don’t remember which browser ended up working (cookies were always cleared every time). Also your behaviour post-creation might matter. You want to look as real as possible, and that might involve posting a human looking comment on a trending post in /r/askreddit or something.