All of these firms use Game Engines? Or maybe everyone on Twitter used too much hyperbole.
I dunno, I recently started working with a car audio DSP platform that has companion apps for windows, iOS etc. These apps are basically glorified equalizers with a couple more advanced functions, so the interface is done with sliders, knobs, text boxes, etc. Basic GUI stuff. But the apps were built in Unity, presumably to minimize cross-platform GUI bugs and ease of portability.