Definitely put it behind Netbird.
Also. I have a Jellyfin instance that I share with family, where I actually can't put all of their client devices behind Netbird.
For that case, I used Netbird's reverse proxy feature. So technically the Jellyfin instance is exposed to the public internet. HOWEVER, Netbird allows you to block or allow certain IP addresses. So while my Jellyfin instance is technically on the public internet, it's only accessible from 1 specific public IP.
Otherwise, if you're on the Netbird VPN, then the domain I have set resolves to the internal IP.