To setup music manager, I install the "YT Music PO Token Generator". I'd like to reuse this outside homeassistant. How can I open the port it uses so that I can send requests from other machines on the network?
Is it as an HAOS app (formerly Add-On)?
are you trying to expose this on your Public IP (anyone on Earth can talk to it), or just on your local network?
If it's an HAOS app, you just go to the configuration tab and look under Network, if it's a normal app. You will see the suggested port in a small font, just type that port into the field and hit Save. That will expose it to your local network.