Most bass traps are velocity absorbers, not pressure absorbers.
While the terms pressure absorber and velocity absorber get used, in reality something has to move or there is no absorption, so all absorbers are velocity absorbers. At ASC we consider our TubeTraps to be pressure zone absorbers, meaning they do their work when placed in a high pressure zone, like a corner, by converting the pressure to velocity as the pressure outside the trap causes flow across the fibrous membrane to try to equalize to pressure inside the trap. The flow creates heat, which absorbs some of the sound energy. The bigger the volume inside the trap relative to the surface area of the membrane, the lower the absorption can go, which is why bigger diameter TubeTraps can work down to lower frequencies.
There are traps that can work in velocity zones, where sound pressure levels are low but air movement is relatively high. These would inevitably create some pressure in that zone as they slow the air movement through friction, converting sound energy to heat. These would need to be larger and less resistive than a trap working in the pressure zone.
It's conceivable that a real pressure device could be made without moving parts. One I could imagine would be some method of rapidly heating and cooling the air in the corner of a room in a manner out of sync with the pressure swings. If you could cool the air rapidly as it's trying to compress in the corner, and then heat it rapidly as it's trying to expand you could reduce reflection out of the corner. Maybe a dense grid of very thin heating wires hooked up to an AC current working against an air column of cooled air created by a interweaved grid of tiny cooling tubes.... Nah. If something like that could work it could also be used a subwoofer to generate sound.