Yeah I also joined Mastadon years ago but could never really get into it. I should look more into your Consensus. It matches a lot of my own ideas. I do indeed want to see media platforms more owned by users.

One problem I see, which I struggle with where my socialist beliefs crash with my beliefs around how to run companies, user interface design etc is that open source communities have generally been rather bad at creating quality user interfaces. They tend to become too geeky. Systems built by geeks for geeks tend to suffer this.

A corporation in contrast builds a product for average users. It is not geeks just building stuff for themselves. That has some important implications. Thus purely voluntary organizations may not work. I think you might need heavier government involvement in some sense or something structured more like a non-profit organization serving the people rather than simply an open source project.