I wouldn't know how to access Jellyfin through tailscale on a Android tv that is not in the same network, and that wouldn't necessarily be sharing.

I think the most relevant thing is that using DDNS implies exposing to the internet which for many self hosters is a big no no. As well if you only want one or two machines , maybe tailscale can be a very easy way to setup… I guess it boils down to the OPs needs.

I would look into setting up Jellyfin as others said, there's multiple guides everywhere but you will need some knowledge for setting up a nice URL in case you want to access it from the internet, that's when you want to search for things such as free ddns… But it's quite a lot by then maybe