In astronomy/astrophotography the FITS format[1] is commonly used, which supports all these things and is, as the name suggests, extremely flexible. I wonder why it never caught on in regular photography.
Especially for really old setups that had RGB color wheels and multiple exposures, exactly like a multispectral astro image might. Phase one also has a multispectral capture system for cultural heritage, which just shoots individual IIQs to my knowledge… It would work great too for multiple pixel shift shots.
Possibly, the engineers just didn’t know about it when they were asked to write the firmware? It’s funny, I think most RAW formats are just weird TIFFs to some degree, so why not use this instead.
Considering how often I witnessed engineers trying to build something to solve a problem instead of sitting down and researching if someone else did that already, and likely better, I really wouldn’t be surprised if that is the answer to most questions in this thread.