I'm referring to this library https://google.github.io/modernstorage/photopicker/

So, I don't see the point 🤔

it’s not limited to what’s physically on the device storage: one can search Google Photos for example

Believe me, I know all the advantages, but I also know that system picker has inconsistent behaviour, we did quite a lot of research in this area in our app, and I was against in-app gallery picker, but after all research and reports of all possible problems with image picker I was actually convinced that in-app picker is not the worst solution

so we ended up with in-app picker and optional permission, without permission user just can use system picker so any storage access framework integrations are still available