Using a restreamer to watch TV you already pay for via your ISP (like MagentaTV) on different devices in your home is generally considered a technical workaround for convenience.
Before touching code, we must define the term. "Restreaming" in the IPTV context refers to taking an incoming video stream (typically an M3U8 link, RTMP stream, or UDP multicast) and rebroadcasting it to a different audience or device. Iptv-restream Github