If you'd rather set up your own server, here are some links to help you get started with that.

You can download/install the Pleroma software to create your own server by following the instructions on the documentation.

Pleroma had a bug in how it dealt with presenting itself as a different name from the one it's configured for internally (see How to use a different domain name for Pleroma and the users it serves), which was supposed to be fixed in the 2.5 release (though we haven't confirmed that it was). We'd developed a workaround for that, and the instructions for the then-supported (2.4.4) version of Pleroma is here.