From what I understand (which is pretty sketchy) , the vaccine is most effective if it binds to cell membranes and GO does just that . Perhaps it has an affinity for both the lipid used to encapsulate the mRNA and the bi layer lipid membrane of the cell. With the size of the GO nano particle there would be multiple functionality sites for attaching both without serious steric hindrance issues. If so, pretty elegant in approach as long as you can mitigate the downside risks
As I understand it, the nanoparticle delivery system, a triple layer lipid envelope, was the hardest part of making mRNA vaccines viable. GO is already widely used in other therapeutic drugs for delivery of biomolecules and antigens, and was being pursued as a vaccine adjuvant and carrier, so it wouldn't surprise me if it is used by Pfizer/Moderna. This is part of the intellectual property Biden wants to give away to China.