I’d go with grimshot then, which I think works for hyprland as well (it’s made for sway). It provides an interface over Grim, slurp, and jq, and makes life easy. Combine it with a image viewer like imv, and your set!

grim + slurp ftw. On my system mod+ctrl+s -> select area by drawing a box -> screenshot saved as shot.png in the Downloads directory where even sandboxed apps can read it. Next shot just overwrites the previous one.