External hard drive and iPad...

How hard can it be? I've an external hard drive which contains legitimately purchased iTunes movies which I'd like to play on my iPad... sans laptop.

Why is this simply not possible? Despite the seemingly endless stream of software updates, the high initial purchase price, the wonderful customer support and the incredible marketing we still don't have access to what should be a basic function.

What gives? Should I throw in the Apple towel and buy something that actually does what you expect it to do?

Come on! This is 2018 and I'm getting old!!

Please tell me the solution.

Cheers... Paul