I'm back on track after my login was somewhat broken...
I use Xorg - came automatically. The nice of actual Linux is: It is a little bit like Windows. Installation is close to automatic.
Gnome Screenshot I have never tried.
If available original software is always better.
I tried it. It is far from the options Flameshot offer, but sufficient. (Flameshot and Shutter have an edit function as well) but it works really well.

By the way: It seems the opportunities are not really visible. It is not easy find all these small good programs.