Or allow me to make my own categories based on apps. Here's an extreme example: meditation timer. All I need you to do is ring a bell after 30 minutes, otherwise I'm meditating and obviously not looking at anything but the wall. So I'd like $TIMER_APP to not count toward screen time. Instead, it racks up 30 minutes every day toward that number. Does the yoga app that I throw to the Apple TV count? I guess it does.
Should it count? Depends on what I'm trying to measure. If Screen Time is a measure of "sitting on my ass swiping at a piece of glass", then no, yoga time is not Screen Time. But it's early days, perhaps they'll refine it into a more useful feature.
Now, Screen Time does do what you're asking. Screen Time/See All Activity/Show Categories. It's not perfect. Messages shows up as "social networking". Okay, if that's what you want to call "telling my wife I'm not dead in a ditch" and "hey, neighbor kid, wanna walk dogs with me?" But's it what we've got, and it's better than what we had.