First of all, most media players are streaming/network capable, they don’t even advertise it. Just feed it the URL.

You can even integrate user/password combos for http simple auth into a direct link. Not the safest; just to avoid people getting wind of a free radio station and overloading your server. Unless that’s you want, but then you should be aware of legal stuff.

On the server side, you can run your own radio station with something like Icecast. That’s its own topic.

If you want to choose what you listen to remotely, you are most likely looking at something Subsonic-compatible (apps exist). People say Navidrome is good. I am currently running jellyfin, it’s not subsonic compatible but apps exist, too.