Free select screenshot tool for Pop

Hi all. New to Linux, just installed Pop yesterday. I'm trying to find a screenshot tool which allows freeform selection, something which was built into Windows via snipping tool. I've tried Flameshot, Shutter, and a half dozen other programs but either I'm blind or none of them have this functionality.

Can anyone recommend a program that does that? Thanks!

Edit:

Clarification: I want to be able to draw a shape, say a circle instead of a rectangle, and have the screenshot only be of what I've circled. Snipping Tool in Windows had this functionality, you could select that instead of a rectangle or square it would be freeform. I wanted to know if there was any Linux equivalent, because I haven't been able to find one on my own.