Is there a way of making photo diodes with the shuttle? Or would it need a different package. Could we get bare dies as part of a shuttle run to wirebond and then do sensors?

I’m hoping to do an imager too — so hope to find out re: this

Did you see this? https://efabless.com/projects/425

I hadn’t! I’d wanted to do an entire imager though — so APS like configuration to be able to pack ‘em in

AFAIK photo-diodes need process support and can't be just added by an extra package. For example a image-sensor tech I used in the past had reduced number metal layers and with reduced thickness compared to the regular logic process. In the project linked above I don't dummy generation block layers were drawn in the design otherwise your photoDetector will be covered by dummies in the metal layers.

Don't we have a way of specifying fill avoid areas?

Yeah, you can definitely exclude dummy fill from certain areas. As long as we aren’t looking for an amazing QE number or something, cmos ought to be ok?