^^^What GerryAZ said. The tire pressure placard inside the door is in PSIG, so even if the TPMS measures absolute pressure it has to convert that to gauge, which is the difference between the ambient air and the air inside the tire, and is what a tire gauge measures. Otherwise, using a tire pressure gauge makes no sense at all, as you would have a reading varying by 14.7 PSI +- a bit depending on local air pressure.
Guy [I have lots of experience designing/selling off-grid AE systems, some using EVs but don't own one. Local trips are by foot, bike and/or rapid transit].
The 'best' is the enemy of 'good enough'. Copper shot, not Silver bullets.