There's not a lot of technical knowledge you need to run a jellyfin server. Download the software on your PC, install and point jellyfin to your media folders and you're functional on that end. Download and install the jellyfin app on your streaming devices (roku, firestick, shield, whatever), your tablets, phones and they all have access to your personal media library anywhere that they're connected to your home network.
If you want to be able to do what I'm doing and stream while away from your home network (and it literally doesn't matter from where, as mentioned I'm in GDL right now and have access to all of my media, as long as you have internet access where you are and your server is running, you're good), you need a peer to peer mesh vpn software installed and configured (sounds more complicated than it is in practice and setup). That creates the secure "tunnel" for you to connect to your home network to from outside of it. I use a vpn app called Tailscale for that. But if you only ever watch or listen to your stuff at home, that's an extra step you don't need.
The only other thing you need to know is how to acquire, store, and organize your own media. Whether you prefer doing that on the high seas or just digitize your own library of physical media, that's up to you. You're not limited to just movies and shows either. It streams music as well and also has an e reader built in so if you have a library of ebooks, just point jelly fin at the folder and you can access your library on any device.
The knocks on it are 1) the acquisition piece. You have to actually have the media on the PC you've installed jellyfin on...by whatever means you're comfortable with & 2) the storage required to have a large library. I'm running on a 6tb external HD for now, but I definitely see how that won't be enough forever as my family starts to use it more and the diversity of content on the server forces it to have more and more content for everyone to be happy 3) Your PC is off? Well, so is your media server. So "up time" becomes a part of your vocabulary. Now...multiple instances of jellyfin on multiple PC's can be strung together seemlessly to add redundancy if you care about those types of things. Eventually I might, currently I don't. The spec requirements to run this is actually pretty minimal as well, so building a full time server from left over components or some rando cheap PC bought off of marketplace, shoving it in a closet and leaving it on forever is completely viable as well.
Fwiw, I tried IPTV for a bit, but other than live sports it was a pretty meh experience. I prefer the streaming model to the schedule TV with a billion channels model. I want to watch what I want, when I want to watch it. Not what's available to me at 8pm according to a broadcast schedule.
This is the easiest/best way to replace streaming subscriptions though, control the content you have access to, and run everything (movies, shows, music, books) off of one central app.