working with other targets
There are react-spring targets other than three.js (https://github.com/react-spring/react-spring/tree/master/src/targets) like konva and babylonjs that I think would work really well with your GUI controls.
I forked your repo and got it working with BabylonJS (works on a new react-babylonjs branch only for now).

So, curious if you were interested to remove target dependencies to make more generic or if you intentionally have it as three.js only. Great library and especially like the xypad!!
That would be great, I do plan to make the library multi-target. Can you make a PR with it working for babylon so I can see the changes needed and plan for re-architecture for that?
I'll make a PR - will have examples for three and babylon. I will first put out a new version of react-babylonjs that handles the "spring value" type to ie: rotation-x. I need a few days. Cheers.
the loader prop I just found. that's a hard dep on three, so will need to consider how that fits into the API.