Yes, it is possible to do pressure detection using CapSense technology. It typically requires two electrodes placed in parallel and a non-conductive material that can deform. The non-conductive material gets placed between the two electrode plates. When there is pressure on one the top plate, the non-conductive material deforms and the distance between the two electrodes reduces resulting in capacitance change. This change in capacitance is proportional to the pressure applied.
Currently we don't have any details regarding the type of materials for the electrodes and the non-conductive material.
But, it is possible with CapSense technology.
Do you think what you describe can work with using copper pads on two PCBs between an air gap?