Check out the latest blog on Boss Room which has been updated to release v1.1.0-pre and boasts a whole new feature set for developers looking to explore the services side of multiplayer game development!
This multiplayer sample game features a variety of UGS in a production-ready environment for developers to learn about multiplayer game development. Let me know if this helps you get started: Enter the Boss Room in 2022: Netcode for GameObjects, Relay, and Lobby