You mean something like this?:
Problem with this method: decals don’t work, but you can take a plane and place your “decal” on it with this material. Maybe there are better methods, but with this you have a starting point(?).
Nope, not my idea, posted by these guys:
UE426_UVLight.zip (1.2 MB)
UE5_UVLight.zip (837.4 KB)