That’s the whole point of a domain. Your IP changes every now and again you need people to know where to reach you. You give them a domain, and you configure the name records so that the domain always points to the right IP address.

Your options:

• dynamic IP - you keep your setup as is and just periodically tell them the new IP you’re on. Annoying and exposed
• static IP - you buy a static IP (from your ISP) and share it with your friends once. A little bit less annoying and still exposed
• you use a VPN like hamachi or radmin - your friends install the software, they look for you IP in there, you’re done - very secure but also very annoying
• you buy a domain - you have to configure an IP updater like ddclient or similar, then you jellyfin should be reachable - least annoying for your friends but also slightly less secure

Domain is the cleanest option.

I am telling you how annoying it is because that’s how likely your friends are to adopt it and how secure it is because depending on your country you are doing something illegal and you really don’t want anyone to find out and you gotta keep it updated more often if you don’t want people to exploit it. There’s an endless supply of very smart people out there who use known bugs to target public services.