The idea of there being “foundations of reality” is preposterous.
It can even be said that talk of “the nature of the world” (rather than, say, the plural natures) begs a few questions too. In addition, why accept any distinction between abstract and concrete objects? Or, alternatively, perhaps there are other kinds of objects. Perhaps some metaphysicians even question that there are events in the way that others question the existence of objects. And so on.