iPad on the audio signal path

I can route MIDI from VCV Rack to my iPad (into an app like Animoog) and then return the audio back into VCV Rack (via MacOS’s built-in Audio MIDI Setup). What I haven’t been able to figure out is a way to route an audio signal from VCV Rack, through the iPad (through an effect like Moog’s Flitatron, or Eventide’s Blackhole Reverb*), and back. (In other words, I want to use the iPad as an external effects processor or digital stompbox.) Has anyone had success with this kind of thing?

*on sale through today, btw