I would be satisfied with a global curve, but I must to recognize that one curve pressure for each brush give them its own characteristics, that can be very different between brushes.
For example, the feeling and way of use of one watercolor brush can be quick movements with barely strength pressure for light washes. And the opposite for an oil impasto one.
As you want but please, almost one
Anyway, I must to say that Artstudio Pro is the reason to have an iPad Pro (not Procreate, not Affinity).