I have remote access for Jellyfin using a domain I purchased just for self-hosting. Using Nginx Proxy Manager (NPM) and a dynamic IP service. NPM handles directing the incoming traffic to the correct server. I point a subdomain back to my Jellyfin server. When traveling, I install the Jellyfin app on a smart TV where I am staying, or connect my laptop to the TV and just use the web interface and my subdomain. I also use the Jellyfin android app to connect remotely using a phone or tablet.
At home all my TVs use a Roku and the Jellyfin Roku app to connect locally.