Create a directory of MP3 files of the music you want on something like a Raspberry Pi or a disused older computer you can install Linux on to dedicate as your streaming server (assuming you want this to run 24/7 with no interruptions, if you want to do it on and off, you could just use your PC and schedule things like rebooting for when you’re not streaming). Then have a music player like VLC play the files in the directory on loop (and optionally shuffled). Then set up your stream on OBS or a dedicated Peertube streaming app. For visuals you can either just have a black screen or static image, use a dedicated music visualizer app, or even just stream the UI of the music player (which will display the name of the song without any extra setup).

Just streaming audio with mostly static visuals doesn’t take a lot of resources. Audio doesn’t use a lot of data and static visuals are very compressible. You can probably get away with pretty much any computer from the 2010s or newer. Hardest part is probably picking which Peertube instance you want to stream on.

Also, you don’t even need to use Peertube unless you specifically want it to be discoverable from there. You can just host a raw MP3 stream and the default audio player in your browser can play it if you go to the URL, as can VLC. I listen to live air traffic control audio sometimes and the sites providing it just give you a URL to a raw MP3 stream and an accompanying playlist file you can import into your music player.