I’m using Zoho. It’s pretty cheap and wasn’t hard to set up with my domain.

If the network the cameras connect to has no way to reach the Internet, then the cameras can’t reach the Internet.

On the positive side, if your vaultwarden server dies, the cached vault on any/all of your devices can be logged into and export the vault.

Why would your Jellyfin traffic need to go over the Internet if it’s on your local network? You should be able to install the Jellyfin app on your smart TV/Roku/etc or use the web client from a computer, point it at the Jellyfin local IP address, and view it over your LAN.