iPhone photo backup to wifi hard drive

My daughter is going to Europe with the Foreign Language club for a week this spring break. I need a way for her to backup the photos from her iPhone while she is over there. We do not have a laptop to send with her, and I do not know how often or reliable their internet connections are going to be while over there so I cannot rely on iCloud or other cloud storage.

Can any of the wifi hard drives offered be used as a backup device for her the photos on her phone? Or does anyone have any other way to backup the photos from an iPhone without having a computer?