You are correct. Streams is Fediverse software that you install on a server.
I initially misunderstood your question, so deleted my post. Sorry about that.
Yes. Synapse is the server side part of Matrix. You install it at a Matrix host, or on a VPS, or even a Raspberry PI device. See https://github.com/matrix-org/synapse#installing-and-configuration
Once up and running you connect a client like Element to it.
Setup a Koel instance at a host of your choice. Upload your music to it and stream from that. See https://koel.dev/
Cell phone tracking is common place. If you carry one, you're being tracked, profiled and having your data correlated with others. The question is whether you support living in a surveillance society. If you do, grab a cell phone and be happy. If not, get rid of it and use alternative communication methods. It's a simple choice. In my experience, most people choose convenience over privacy.