The statement that electric pressure cookers measure pressure absolutely (i.e. not relative to local pressure) was news to me, and definitely a good hack to know if you're living at altitude.
I'm less certain the same transfer function always returns the gas pressure at the top of the sealed bowl "no matter what altitude you're at" considering that at the starting point, when first sealed, ambient room atmospheric pressure varies with altitude: for the same initial food mass to be cooked the standardised gas volume included will vary with altitude.
(Alternatively, no matter the altitude, there's always a constant volume to fill with atmospheric gas .. and the mass of that gas will vary with altitude)