Given that you need to pass --expert to gpg 2.1 as of right now to even generate an ECC keypair for PGP use (nor use one on an OpenPGP smartcard or yubikey), I can sort of forgive the lack of ECC in 1.0. I don't think it sees wide usage for PGP keys (some clients don't support it, also).

However, as of the last time I tried Protonmail (about 10 minutes ago to check this is all still true) you can't: revoke/reissue your PGP key, validate outside signatures (either on encrypted messages or signed, plaintext messages) or send pure-PGP mail to users outside of protonmail (there's an encrypt for non-protonmail users option, that sends a link instead). Essentially as another commenter has said, you can't really do PGP with ProtonMail.