Tim Cook admits that iPhones use Sony camera sensors

Is this a big admission? There are only a handful of volume phone sensor suppliers. Anyone skilled in the trade would be able to identify the maker with a scan of the sensor (or disassemble the phone and check the part number). And, the sensor only gets you so far, sophisticated software can make a given sensor produce better final images, as Google has been demonstrating for several years.

Not much on an "admission"? They get that part from a supplier, who unsurprisingly is a large player in the space of part in question

I thought that was known by everyone. The big thing is how the software deals with the raw data and that is different for each phone maker.

Certainly not a "big admission". Apple does not make a secret of its relationships with important suppliers (Qualcomm, Corning, Samsung, Foxconn and so on).

Though TBF it is unusual to have a press photo of Tim Cook visiting Sony! I imagine Sony negotiated it into a supplier contract.

The sensor hardware is probably the least interesting part of the iPhone image capture pipeline.

A total paid PR piece, not even news.

who else can even make sensors of that quality?

Even among high end digital mirrorless cameras, only leica and cannon to my knowledge, don't use sony sensors.

nikon, hassleblad, fujifilm? all sony sensors