The Big Bang inflation: Ultra Slow Pulsars are observed: SMBH Binaries Supermassive Black Hole Binaries with dual jets, a : SGWB Stochastic Gravitational Wave Background.?

According to the Q-FFF Theory, the Big Bang is the explosion (Splitting) of the older Big Crunch String Black Hole Nucleus (Singularity) into smaller supermassive String black holes compacted by the oscillating String vacuum. (SMBHs, and not SGWB)

As a consequense, the early universe starts with multiple splitted smaller string knot nucleus black holes able to form travelling Tadpole black holes forming filaments of plasma and stars later observable as the cosmic structure (H.Alpha)
However also forming SMBHBs or Herbig Haro DUAL black hole starforming systems ejecting Jets with 2x bowshock black holes at the top forming an Ultra Slow Pulsar by slowly roation of the dual central aligned jets acting as a gravitational lighthouse, which is observed by the NANO-grav and LIGO-VIRGO system antennas..
See: Three sorts of galaxies:       

1: Single Tadpole Primordial Black Hole based Elliptical Galaxies with one BH in the center,

2: Herbig Haro Star-Galaxy formation with dual equal sized black holes out side the

Galaxy (GABHs)  Galaxy Anchor Black Holes.

https://vixra.org/pdf/2101.0158v1.pdf

3: all kinds of merger gaaxies like irregular etc.

and: https://bigbang-entanglement.blogspot.com/

see also discussion :

Constraints on ultra-slow-roll inflation with the NANOGrav 15-Year Dataset

https://arxiv.org/pdf/2310.20564.pdf

Conclusion in contrast however: Q-FFF model says: the SMBHBs idea seems better the SGWB system

see also: New Physics by Table Top Experiments.

https://vixra.org/pdf/1309.0081v2.pdf

Below: Q-FFF String theory principle models. (Quantum-Functin Follows Form)

Below: peanut shaped early dual Herbig Haro systems direct after the big bang.