I was thinking the flywheel may have been off a sewing machine originally?
That almost seems likely Nick, as they often have a heavy enough rim to be able to turn it square like this one. Except that this one has some nubs on the spokes that could/would catch up cloth or thread, and be a real hinderance, if any got caught up on that side of the machine.
I think all the sewing machine hand wheels that I've ever seen had simple straight spokes without any embellishments. But, no doubt, I haven't seen them all!?!?