I want to develop a music player for Google home, I can't seem to find any resources about that.
Please note that I'm not trying to build a mere action on Google Assistant. I want to build a music player that streams audio, etc. just like when you say "hey Google, play music on Spotify"
Take a look at Content-based Actions: https://developers.google.com/actions/content-actions/ If you have a podcast then that should be the easiest to integrate.
If you have a media app or service, then deeper integration with the Google Assistant is currently only available for partners: https://developers.google.com/actions/partners/
You can contact the support team if you want to pursue this more.