More or less experimental stuff that gives hope: nostrmail, cordn, obscuravpn.
https://eylenburg.github.io/im_comparison.htm
quotingAhh, I got it, this specific page works okay:
nevent1q…dp8k
`https://account.protonmailrmez3lotccipshtkleegetolb73fuirgj7r4o4vfu7ozyd.onion/start`
This one attempts to send clearnet requests:
`https://account.protonmailrmez3lotccipshtkleegetolb73fuirgj7r4o4vfu7ozyd.onion/mail/signup`
