An origin story beginning with a singularity is not ex nihilo. It relies on space, time and physical causation.
That is the weakness of all such theories (inflationary, multi-verse, multi-world, ekpyrotic, cyclic, imaginary time, etc.) Because of the CMB measurements, we know the universe is expanding, i.e. that there was a beginning of real space and real time.
As Jastrow said (paraphrased) that was the most theological statement ever to come out of modern science.
Well, yeah, I knew that.
Which is one reason why science has nothing better to offer.
What they propose doesn’t even work under their conditions.