Earlier quoted context omitted.
But they didn't reverse engineer anything, afaik. Their Android app is just talking to a Mac Mini somewhere in a closet, logged in with the users Apple account (or so was stated in one of the interviews).
Okay, automating Apple account logins on a fleet of macOS VMs is still rarely treaded territory, so it takes some real technical chops, even if it’s mostly stitching together other people’s work. TLS termination on the hand takes <1hr following a guide, if you haven’t done it hundreds of times before…
The hardest part is probably keeping the duct-tapped stuff running.