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Matrix/Element is great. https://matrix.org/clients/

I understood that P2P is delivered by the Pinecone overlay network which is in the makings and none of the available clients yet provide P2P communication?

Well, in fact they have a CLI client ( that I haven't tested ) [1] and their site says they're going to be available also for Mac, Windows and Linux.

https://github.com/berty/berty

in beta still but https://briarproject.org/download-briar-desktop/ is worth a look