The best option is to get a device that has more storage, you'll always be getting rid of image clarity by compressing it, the average photo taken by a mid range phone camera is gonna be a minimum of 3MB and we live in an era of affordable Terabyte flash drives.
What a piece of junk !
I imagine its old hardware but still, Jeez.
What ought to be the simplest thing was turning into a multi-hour nightmare fast.
It seems the "Sony picture frame gizmo" is only meant to read an SDcard literally removed from a camera & NOT copied or downloaded from a PC/phone etc.(That was my specific issue anyway but its ...