There are numerous theories about the singularity at the start of the Universe (or Multiverse) and the paradigm in which it existed. The General Theory of Relativity extrapolation regarding gravity reduced to time=0 has the point infinitely, vanishingly small. No one actually understands what occurs to either mass or energy in such a state. Some believe it stops shrinking to nothing somewhere (maybe because time has stopped too) and is stable, fair and balanced before quantum uncertainty makes it jittery and it explodes then hyper-inflates for a fraction of a second.
That’s all speculation. Quantum mechanics don’t work at that level. People have invented pre-big bang theories and view the t=0 singularity as a kind of middle of an hour glass that another Universe collapses in to with gravity before exploding outward. There are DeBroglie-Bohm and Everettian versions of quantum mechanics differing from those of the standard model of the Copenhagen Interpretation and they would allow different ideas about the singularity (unless it was a membrane instead of a singularity) to be made.
The mass-energy of the Universe compacted to a singularity could be configured in as many ways as human imagination allows. I like the idea about Divine Mechanics. Some prefer Tegmark’s concept of the Universe composed of mathematics in-itself. A point is a zero-dimension thing, If a point with a Universe full of energy-mass existed it seems as if there could be no virtual particles around it since that energy would be attracted to it as should everything else across empty space.
Virtual particles are something like ghost super-positions of particles that actually exist. It could be that the singularity had a quantum cloud extending in all possible positions across the empty space where it was not. Even the quantum cloud would have used some energy-perhaps equal to the amount of energy in the singularity; yet I am skeptical of that.
One wonders what sort of energy would contain or define the limits of superpositioned particles of the cloud centered on the singularity; if there is a Multiverse would the superpositoned cloud be limited to just one Universe or all possible Universes? Would the quantum cloud of any particular Universe interfere with the cloud field of others?