> Has anyone used these in games?
No doubt someone has put some of them into games. However, most likely not in it's original shape/form, as the scans usually produce highly inefficiently (but high resolution, great for renders) meshes. The meshes from scans tend to be a mess, and when inserting a 3D model for games, you care a lot about how optimized the meshes are, and that the mesh has a low polygon count as otherwise you'll tank the performance quickly.
So since a developer couldn't just copy-paste the model into the game (requires a prepass to fix issues/optimize before import), it'll take valuable time from other things for just this easter egg. Again, no doubt someone has done this at one point or another, but that's probably why it isn't as common as someone could think.
As an example, take a look at the wireframe of the Rosetta Stone (https://i.imgur.com/rtpiwjZ.png | https://github.com/BritishMuseumDH/rosettaStone/blob/master/...) and you'll see what I mean. For a high quality rock-like object, you'd probably aim for 2000-5000 triangles, while the Rosetta Stone scan seems to have 480,000 triangles straight from the scanning software.
Sadly, it's simply too much detail to be able to import straight up. Luckily, Nanite ("Virtualized Geometry") and similar implementations starts to give us tools so we can stop caring about things like this and let the game engine optimize stuff on the fly.
