So I have family that lives outside of reach for internet in the country where they are. I was trying to find a way to take an android tv dongle(with an SD card) and make its streaming apps have the download options that are available on mobile devices so they can plug it in when they're in town at work (possibly on a portable screen) and download some stuff for when they go home. (Their mobile data gets charged badly if they try to stream their phone. And streaming services don't allow screen sharing downloaded content)
Only option i see is sideloading the mobile equivalent of the apps to get the download features, but the layout will be designed for mobile and touchscreen.
Really there is no simple method for this, tv devices and apps expect an internet connection as its within a household