Sorry maybe i missled you guys.

The problem i have with the GL-X750v2 router is, i want to use it in greece and half a year ago i had original openwrt running on it, and it did not constantly connect to lte for whatever reason. (Same sim card in smartphone at same spot worked).
So this time i am trying the original firmware of gl on it. Both (openwrt and gl firmware) work perfectly in germany.
Now i want to be able to swith back and forth between the two to try in greece with maybe no internet availability and a person using it not very capable of working on it beside doing a uboot image file upload.
So that is why i am asking if there is a way to totaly backup/copy/create an image file to put on and it works. Also for a second device as backup f.e. later on after proof of concept.
Like using clonezilla or rsync the /etc folder or whatever