Nextcloud crashed, Joplin data gone 😱! Restore from "local" possible?

Hello,
Is there such an option of "Re-upload local data to sync target" as well for the mobile application?
I could not find anything.

I had a data corruption, where quite some images on my PC's joplin/resources folder where overwritten with zeros (filesize remained, but content replaced by binary zeros) and on the sync target it is the same. I do not know, where was the source, and where the consequence.
But I realized that in the mobile app there are (at least some) photos still working, apparently not overwritten. Apparently the sync did not touch them, therefore luckily they have not been replaced by the zero'ed versions.

Now I am wondering, how to get these uncorrupted resources out of the mobile phone to restore them everywhere else.
Do you have an idea?