You have 2 options:
1 - Open up Jellyfin port (8093) in your router if you are not behind a cgnat and add a reverse proxy
2 - Get a small vps and a domain, install a reverse proxy and use tailscale to connect the vps with your home server, point your domain to the vps and forward traffic to jellyfin.
Just remember that using funnel for streamimg servicies it is against the toss.
You should keep trying with tailscale, did you read the docs? (tailscale provides amazing documentation), you dont need to install the client on every device, for that use subnet routers, all is in the docs. Give it another try and post back what issues you are having.
What is the use case? Share with family and friends?