Is there a good reason we don’t have a streaming stick that can download for offline playback

Hulu, Netflix, and Prime all have download for offline viewing on my phone. Why can’t I do this on my FireTV or Roku.

I know we’re limited by the device hard drives but it seems like amazon would welcome a reason to sell an upgraded hard drive version of Netflix would allow downloads.

99% of the time I wouldn’t need this but it would be a lifesaver at hotels with terrible wifi. Hell I might invest in a little back of the headrest tv for car if I could preload some shows for my kiddo to play on long road trips.