A M43 sensor really isn't very big, only around 80% larger than the 1" sensor in the
M2P and that drone has a very small camera housing/gimbal. The
M3 camera housing looks significantly bigger, as far as we can see in the photos anyway, even ignoring the telephoto camera above it. All current leaked material still suggests a M43 sensor and it makes sense now that they have a 1" sensor in the
Air 2S that something bigger/better should be in the
M3. A 24mm F2.8 lens with a M43 sensor only needs to have a (minimum) front lens element diameter of 4.3mm (the actual lens, not the housing), which doesn't look unreasonable at all based on the photos.