Took my friend out to the park to escape the hellish news cycle for a bit.
This was done by hacking an ARCore demo via the Unity3D game engine, viewed through a first-gen Google Pixel. The little bits of animation were drawn in Clip Studio Paint, exported into a Unity sprite animation.
I feel like I understand the basic concepts behind AR, but there was so much to learn in order to get this far: finding my way around the Unity environment; a bit of the C# language; the scripting engine; how to actually create an animated sprite; a bit of Android development kit, et al. I still don't understand how everything works, but just like fixing an old watch, you can learn a great deal from tearing stuff apart and reassembling it.