If this hits you in the nostalgia, check out this project[1]. It uses raspberry pis to broadcast content over "channels" using existing coax to simplify finding something good to watch.
[1] https://hackaday.com/2020/02/07/raspberry-pi-serves-up-24-ho...
Alternatively, this project hooks up to an existing Plex server and allows you to build channels that can then be connected to over the network (VLC, or anything else that can take a stream, including Plex’s live tv function).