Do you live in a vacuum?
I don’t mean a rhetorical one, but an actual physical one? If not then the pressure value for the equations is 27.2, for 12,5 PSI, since the football is surrounded by an atmosphere of pressure.
Not sure what you are trying to say. If you go to the link I provided you will see that the chart is relative to normal air - that is NTP normal temperature and pressure. So yes, it is relational to normal atmospheric pressure.