I use SnagIt to get a screenshot and then I simply use Copy & Paste to get the screenshot in Miro. Idealy I don’t want to show the whole screenshot/graphic on my miro board, because it takes up too much space. I would love to “just” have a thumbnail of the graphic, but still have to possibility later to enlarge / see the whole graphic/screenshot (for example by double clicking on the thumbnail).

My initial question about this feature: https://community.miro.com/got-a-question-ask-the-community-45/graphic-as-thumbnail-3066