User Finder to move subfolders from a flash drive to a Mac

I have on a flash drive from another computer a folder named Pictures with say 10 subfolders. [The nature of a picture file is not relevant to my question.] I insert that flash drive into my Mac Mini.

I want to open the flash drive folder in Finder, select the 10 subfolders there, and drag and drop (move) them to a location under the Mac’s User>Pictures to be subfolders there. Cut and paste is not allowed.

To drag and drop, I would need to be able to see folder structures in both the flash drive and in the Mac at the same time, but this does not seem to work in Finder. If I open folder structure in one, the folder structure in the other goes away. Is this correct, or is drag and drop not possible between two drives in Finder?

Is an awkward workaround essential, or is there a ‘simple and recommended' method for seeing folder structures in two drives at the same time? Or maybe a Move command I overlooked?