Thread aware, exceptions, traditional OO. Guessing because it has features that might line up better with c++?

To me it looks like ChaiScript is more lightweight and easier to learn.

Argueably a questionable advantage over for example lua specifically, where it is already quite easy, while at the same time having all the benefits of a mature production grade system: speed, stability, portability, talent pool, etc. Even Python could be a contester here...

If it's closer to C++ in its syntax I think it's more interesting.

Would that make it a good candidate for microcontroller programming? I have been looking for something more elegant/functional to program arduino with. Anything about memory size on the site?

Not exactly arduino, but you may be interested with nodemcu: https://en.wikipedia.org/wiki/NodeMCU