So you can see your own stream there and see comments as well as the number of viewers. It works with a mobile phone, but it's a bit awkward. Or left on the tv to have a bar where you can see that (but bothers a little). How do others do that?
Most streamer PS4 games stream on the PC via Capture Card, mostly an Elgato + OBS program.
Pure PS4 streamers are rare or have only a few viewers simply because there are hardly any options on the PS4 compared to OBS.