First of all, there's two companies: Semiconductor and Imaging. Sony opens some of their technologies to other customers by transferring Imaging unit's patents to Semi and allows them for re-licensing. So, not everyone is using the same sensor even if they are coming out from the same fab.

Second, there's customer tailored sensor business. Sony can provide a customer a baseline to start and, customer can customize this sensor according to their needs and got it produced for themselves.

Lastly, there's strict division between customers in semiconductor side. So Sony Imaging can't access to specs and design of other customers' sensors.

How it works in real life?

- Sony A7 series use Sony's sensors with all their secrets at their disposal but, not with Nikon's and Fuji's secret sauces.

- Nikon orders customized, "Designed by Nikon" sensors to Sony Semi. Sony Imaging cannot access them (unless they buy and disassemble a Nikon Z).

- Same for Fuji. They have less rolling shutter in XT-4 for example, and it's again built by Sony, for Fuji. No, Sony Imaging can't play with them.

- Canon R5's sensor is "Designed by Canon". I'm not sure they are producing it. Sony or Tower Jazz maybe producing it. I don't know.

At the end of the day, the fab is almost one but, designs are many and diversified and, nobody can see each other's design. Like TSMC and Global Foundries.