I empathize with Levi's situation in responding to various "process-relational" critics of object-orientation. I know from a different context how tiring it is to be making the same arguments and being asked continuing to defend this or that. I find the objects all the way down concept interesting to explore. It is necessarily speculation, of course, and at some point one might begin to wonder what is at stake between the object and the not-object.
Quantum physicists name elementary particles like neutrinos, quarks, and other words I know mostly from Star Trek. We call these elementary because we believe there are no smaller particles from which they are made. Of course, we said the same thing about the atom once upon a time. But let's posit that at some point there is something that is an elementary particle. Now perhaps one might suggest that at the instant of the Big Bang there is an undifferentiated energy mass but that certainly by 10-11 seconds into the universe, these elementary particles had formed. So,if one wants a pre-individual state, perhaps it is there. I honestly don't think anyone knows for sure. Then again, I suppose that within the elementary particle one finds an undifferentiated energy-mass as well; that is, it's not made up of other objects. All these objects were created in the first second of the universe's existence.
What's more to the point is that I don't think such issues are especially important to OOO. OOO philosophers are not particularly well-suited to address the issue of finding the Higgs boson particle. Furthermore, once you start talking about objects larger than a molecule, these concerns are largely moot. In philosophical terms, what you do encounter here is a familiar Derridean problem where ultimately the difference between one and the other breaks down. Eventually, at some level, the object must be composed from the not-object. As such it would seem impossible to define the object as being composed only from other objects. However any object that is composed of atoms is composed of other objects. And the real key to OOO is recognizing that each object exhibits characteristics and possesses a withdrawn nature that exceeds the objects from which it is composed. As such the fact that one can say every object is composed of elementary particles doesn't really tell us very much about those objects. Equally important, the process of becoming does not require returning to the level of elementary particles. When the ingredients of a cake become a cake, they might form new molecular bonds but we are still clearly in the realm of objects.
In short, I'm just not sure why we need to be concerned with that tiniest realm.
By the same token, I'm not sure how important the universe's status as an object is. Clearly not all collections of objects form another object. The stuff in my junk drawer is not an object unto itself. In OOO objects have external relations, outsides. If we posit, as string theory does, a multiverse, then perhaps the universe is an object. It would have an outside. However that just defers the question here to whether the multiverse is an object.
In the end there may not be much at stake in whether we think of the universe as an object or not.
Taken from a different perspective, we might be interested in elementary particles and universes in that they are sensuous objects. Here is where we might bring in Latour and talk about elementary particles as objects formed by supercolliders, as constructions of particle physics. We might similarly speak of the universe as a construction of the Hubble telescope and astrophysics. Of course those sensuous understandings become objects in their own right: e.g. articles in physics journals. But the article is obviously a different object from the particle, though we may trace their relations in terms of an object-oriented rhetoric. But these would seem to be very different philosophical questions.