> PGP as means of encrypting emails is a steaming pile of garbage, as it requires [...] the counterparty to have the same OPSEC as you (e.g. not just forwarding the email unencrypted to someone else)

All encrypted communication protocols have this requirement. And all of them will in the future. By definition, you need the counterparty to be able to decrypt your message, which means you're always vulnerable to them forwarding the unencrypted message to anyone they want.