I have never found protonmail's signup step asking for phone number verification or a recovery email to be unskippable.

Protonmail can still be the best choice for a pseudonymous mail service so long as it's combined with diligent, consistent IP address obfuscation. Protonmail will continue to allow logins and new account creations over Tor. All the major free email providers have long since disallowed new signups over Tor, and most have some form of degraded user experience when logging in over Tor, if they allow it at all. Small, niche email providers appear and disappear so often that relying on them still to exist even a few months into the future is a big gamble. Hosting one's own email requires payment of some type to the hosting provider, so it is not anonymous. Other privacy-oriented free email providers, such as riseup, will do exactly what protonmail did, because if they refuse, their only option is to go the way of lavabit.