Nope.
All DRM ( Digital Rights Management )-protected movies purchased from the Apple iTunes Store must be played/streamed directly from the iPad ONLY.
You can externally just simply store the movies on an external drive, but you need to transfer the movie or TV show, back to the iPad to play it!
That's the way it is and that's how Apple set it up, probably per their various agreements with motion picture and TV studios and agreements with Motion Picture Industry of America.
There is no workarounds and nothing can be done about this.
This is why I stopped purchasing movie and TV series content from Apple and the iTunes store many years, ago.
Too many “put-in place” digital content restrictions.
I have long gone back to purchasing actual physical media or just renting recent movies ( I wouldn't want to own, anyways ) from Apple's iTunes store and delete them from my devices when I am done watching them.