Hi flamingtop ,
Great question! This is not (yet) possible when hovering, though this is something we are working on. For now, you could use the (Premium) Javascript action to make a QR code appear when clicking on the button. Using javascript you can show a QR code, something like this:
const el = document.createElement("img");
el.src = "(url to QR code file)";
document.body.appendChild(el);
You would have to style the element aswell in order to make it appear the way you want to.