@evelyn I've been somewhat surprised to find out you can't just plug your wired headphones into some modern TVs (like most phones nowadays), but you can use one of the HDMI inputs as an output to plug some decoder dongle which you can plug your headphones into. It's called eARC and it's pretty common. And now this!
To be honest, I've seen a lot of odd RJ45 uses too, including connecting the device to its power adapter.