He and the developer of the Pieca camera (https://teaandtechtime.com/pieca-a-raspberry-pi-camera-syste...) have both been tinkering with 1" sensors, which seems to be the current limit for what kind of sensor works okay with the Pi's CSI interface.
I haven't found a larger sensor that is available to mere mortals yet, but it would be neat to get to 35mm someday.