You could just ensure the other party has a key and then send them encrypted text data they could decrypt on their end.

It’s not exactly trivial to add support for this automatically in DMs because of sharing keys between users and ensuring the right keys are in use, considering it would have to be possible to rotate them at any given time.

If you need encrypted communication, use something designed for it. That’s probably the best way to go

Every poll I voted on was overwhelmingly in favor of indefinitely privating the sub. And it was like 7 of them