The smaller/square osmo action 6 sensor would be a wholly inappropriate choice for a camera on a gimbal, and (just like the action cameras) would give noticably worse video quality than the Pocket 3.
The only advantage it would be able to provide is slightly higher res vertical video (which still might look worse), to appease an audience of tiktok kids who have no money, and won't/can't use non-phone cameras.
They're probably smart enough to not use that sensor.
A new leak has revealed updated details about the long-awaited Osmo Pocket 4. Seemingly, DJI will reserve many of its rumoured upgrades for the high-end Osmo Pocket 4 Pro rather than the cheaper Osmo Pocket 4.