I like Protonmail, but its a far cry away from 'real' GPG. They are just now adding SMTP. They don't allow key uploads. They don't let you send (gpg) encrypted E-Mail to non Protonmail users and there are some other problems.
I wish them a lot of luck fixing and working on this stuff.
You can also export your PGP public key and receive encrypted email from anyone else too.