I see you declined this already, but...
Not every device has this function. Mine doesn't.
I tried couple apps, but they seem to depend on the built-in screenshot function (which i don't have).
Anyways, "apps" in FloatingApps have separate apps available (some even built in Android), yet it didn't stop you from implementing them.
Why refuse to add something useful that's requested multiple times?
I just got a bug with your app, now i'll have to use my PC to connect to my device with Teamviewer and make a screenshot to show you, pffff.
See image description - https://imgur.com/394B68F
Anyways, I'd understand if there is some technical obstacle preventing you from adding this function. But to simply decline because you don't want to do it... meh