@threat
> there's a qt client for matrix
That would be Nheko — I'm using it on my Windows machine, it's quite feature-complete when it comes to chats, but I'm not sure it supports voice calls and all that.
And I agree, DeltaChat is a nice option to explore, they have even prepared the scripts facilitating self-hosting email services to be used with their apps — probably won't work for me as they rely on containers, but I can always deploy it in a compatible manner.