I think this is the way, just don’t give it wifi access! Fun story, my sony has android tv and can play MKV files off a flash drive (eg. a non-streaming tv show), but the built in player is horrible (drops frames?). Turns out I was able to find the right version of VLC player and adb the apk over the Ethernet port! Really worked a treat.

This avoided connecting it to wifi, but I still got what I wanted out of it.