TJ Luoma, on Rhymes with Diploma:
Using the Luna Display with my 12.9″ iPad Pro feels almost as if I am using macOS as a native iOS app. The speed and responsiveness are great, and it’s straightforward to use. However, there are some important caveats, especially if you are using a smaller iPad or if you are not using the iPad as a second display for your Mac.
I’m sorely tempted to get one of these, even though I don’t really know what I’d use it for.