Here’s my advice. The most important things are that you have a free GPU slot and another PCIE slot on whatever you get. You’re going to want a GPU for transcoding when disk space gets tight. You want the extra PCIE slot for a sas card. Disk shelves are surprisingly cheap, and you can keep adding disk that way. They daisy chain.
As far as the OS, I’m partial to Unraid and Truenas but seriously, anything you are comfortable with will work.
Santa Paravia en Fiumaccio. It was a tex based strategy game on the TRS 80 written in basic. You played a feudal lord and tried to grow your empire. Each turn was a year. It was a text only game, but I’m pretty sure they had a graphics version at one point. When I say graphics, it was the upper half of the ASCII character set mapped over to block characters. This was in the 70’s.
Not criticizing in any way, but what’s the attraction of IPTV these days? Aside from sports, I just don’t see the attraction. Lots of free sources of live TV out there.