haven’t used the Google migration before - where do photos end up? not all folders are taken into account, see https://doc.e.foundation/support-topics/edrive-sync-details.html
Last I remember, content inside those folders from Cloud will be pulled down to the device if they’re unknown to the device (and weren’t uploaded from the device in the past, then deleted on the device).
There’s a longer thread on the then behaviour where user molej gave a longer comment that goes through some scenarios. Users seem to demand full bidirectional sync, something that isn’t there yet. The code that drives the synchronisation is changing, so things might be different 1-2 months from now.