you are not alone worrying. Besides what this social media profile posts, there is a lot of lively discussion going on beneath. We care for end-to-end e-mail interoperability. A bunch of us are going to the #OpenPGP2025 summit starting tomorrow. There is a lot of specs and standards we follow and contribute to: https://github.com/chatmail/core/blob/main/standards.md

However, multi-MUA compatibility on an e-mail address is a separate issue. #chatmail relays are optimized for instant messaging.