Picasa because it had worked fine. And the replacement, Google photos, is not an option with storing everything in the cloud. Both Darktable and Digikam looks too advance. I think Gwenview will be a good fit. Will try later when she has the time to test. Just viewing the images in the folder, that is all that is needed.
It would be a good idea with the Office 365 but we don’t want things in the Cloud. If the PWA could run offline it would be a different story.