Is there a snipping tool similar to the one in Windows which lets you view it even though you haven't saved anything?
ksnip is pretty much exactly like the Windows snipping tool. The UI looks very alike and you would use it in the same way.
You can install via
sudo snap install ksnip
The source code and other installation options can be found on their GitHub page.
To get more answers you might also want to try the SE site Software Reccomendations.