Yes. I connected my iPad with a cable. If you click your iPad in Locations, then click Files at the top of the iPad window, you should see the Kindle app, then be able to see the files it uses. Drag and drop your file there.
(iPad is away from me, so I might not have the exact details right. LMK and I can hook it up later.)
I also did essentially the same with the Kindle, connected with a cable, found it in Locations, dropped the file into its documents folder.