When Gigapixel AI (ver 6.3.3) is launched from the digital asset manager Photo Mechanic Plus, it runs like a plugin, returning with no warning and replacing the original image. I also tested this with XnViewMP and found the same behavior.
It seems to me it would be logical for Gigapixel to open the same “Save Image” dialog that is uses in the Gigapixel AI standalone before the actual save occurs to assure a non-destructive operation.
(I’m running Ventura 13.2.1 on my iMac).