On you basic question - no, because of DRM limitations you can't put the movies on an external drive with the iPad.
hi
i bought several television series through iTunes a few years ago.
i actually cant remember what i did to get them to a USB, but probably just dragged them from my mac's iTunes library to the USB.
anyway, i am still able (they are Star Trek series and I view them from time to time...) to play these TV programs either in the (new) TV app on my mac and even just in Quick Time on my mac.
they were bought in the USA iTunes store with my USA iTunes ID. and i play them now on my japan iTunes store ID (these series are not available in the Japan store) - MacBook Air has beeb authorized as a device in both stores.
when i upgrade to a new macOS on my mac i usually do fresh installs and i simply just import these TV series into (now with Catalina) the TV app.
i only play these videos on iTunes authorized macs.
its not likely that these have no DRM rights.
my question is: is movies DRM and TV DRM handled differently by apple?
(i also used to be able to play them in iOS 12 before apple split up Music and Movies (TV). now that apple split into separate apps Music and TV i actually cant even see these programs anymore on my iOS iPhone due to Japan not having allowed any TV content in the Japan store TV app. but when it was all one app (iTunes) i used to be able to sync and play these on my iPhone before i upgraded to iOS 13.).