@celia I did migrate my Google Photos library back in March. I basically only needed the files, so I've written a Python script to help me retain all metadata
1. Create a Google Takeout (https://takeout.google.com/) with your Google Photos
2. Run the script on the directory
3. You get a new directory with the photos properly tagged using EXIF and atime/mtime
I hope this can help you :) I'm happy to assist you further if you decide to try this out.
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