Terminology around camera sensor interface module is confusing. MIPI CSI is supposed to be a camera serial interface. Cameras on Pinephone are connected via a 8-bit parallel interface.

I'm also not sure how they came up with 5Mpix in the datasheet, CSI can do up to 4800x4800 which is 23Mpix.

OTOH, 1080p@30fps is not attainable on the parallel interface, at least not with the cameras that are in the phone. It would require ~120MHz clock, and communication starts to break down at around 60-70MHz.