Use XMPP and OMEMO for realtime chat
It would be great if the Minds live chat feature was compatible with XMPP, like the live chat feature in Diaspora. That way, Minds users can be contacted by users on other XMPP servers using an address like firstname.lastname@example.org, and they can chat with folks who are using XMPP apps, like Conversations on Android.
OMEMO is an encrypted chat protocol that can be used with XMPP to encrypt messages, based on some of the same technology used in the Signal Protocol. The Minds chat server could have this turned on by default. You might decide to make it compulsory, so Minds users can only chat to folks using XMPP servers/ clients that support OMEMO and vice-versa, or like Conversation, you could allow users to explicitly opt-out of encryption for a particular conversation with a user whose XMPP software can't support OMEMO.
We are looking at matrix.org right now.
Matrix is also a good option, but its support for encrypted chat is bleeding edge, and turned off by default for a reason. As soon as you turn it on, you enter UX nightmare of constantly verifying new devices, and that's just in one-to-one chats. In group chats it gets worse, especially if there are bridges involved.
FYI another protocol that's in development to support federated, encrypted chat is MLS. Wire is one of the projects involved in the standardization effor): https://datatracker.ietf.org/doc/draft-omara-mls-federation/