Hi blasky,
SmartBase is a term used by Zinus, so you’re probably correct. The concern you’d have with something like this is the spacing between the thin metal rods, with the potential over time for those to press into the base foam of a mattress using a polyfoam core, and the potential for those to bend in a bit as well. Placing a pre-compressed felt posture pad (like what semi-flex foundations use) or a coir bed rug on top of this can be helpful. I go into a bit more detail about this on the foundation thread here.
A bunkie board can be manufactured in a few different manners, but it is basically the bottom wood pallet from a semi-flex foundation covered with a piece of cardboard and then wrapped with fabric. Sometimes a thick pre-compressed felt pad can be used in place of the cardboard. A piece of plywood would of course be a solid surface. The concern with using either on top of a foundation like this would be the potential for noise between the SmartBase and the bunkie board or plywood, and then the lack of breathability between the Bunkie board / plywood and the mattress.
Phoenix