Is it the default? That's all that matters. When GPG defaults to AEAD ciphers, you can say that the ecosystem really supports AEAD (GPG is the de facto reference implementation). If it's not the default, that's purely because too much of the installed base doesn't do AEAD --- there's no other reason to default to PGP's pitiful MDC construction.

GnuPG has offered authenticated encryption for 20+ years now along with everything else that implements the OpenPGP standard.