I don't have any links to hand, but look into Dynamic DNS. It's basically a way for your device / router to talk to your domain registrar, and update their DNS records whenever your IP address changes.

Have a look at DuckDNS as a starting point.

Even without all this DNS thing, you can always reach your own IP from outside. The issue becomes a security issue. You will need to route your PC's specific Navidrome port. You can use any port you like, but you'll need it exposed thru. So that opens your system up for attacks from outside. With the cloudflare thing you can safely access your computer from outside without opening ports.

However you can sort of do this too by adding a couple more pod apps and using a dynamic DNS service. Portainer or cockpit, Pihole, and Ngnix Proxy Manager.

With portainer or cockpit you can organize the pods so they start-up automatically for example. Using your router, split your network into two separate ones ... One for yourself and another for your exposed stuff. Then use the pihole to protect them. Next set-up Ngnix proxy to route to different ports. If you get to my music.com, then it will route the name to a port. Without DNS you can also just route from your outside IP to a local host name. For example 56.45.35.76:657/music could route to NABODROME the local host name or simply to 192.168.7.12. there's a ton of tutorials on how to set these up on YouTube so go have fun. You might choose not to get into all this because it's a little complex. But you could, like many of us, really like it, and then you enjoy a little freedom.

Back in the day I used to use dynamic DNS.