I do “blind” workouts on occasion for this very reason. We discussed it years ago, but the simple solution is to hide your screen via a towel, piece of paper, flip over your device, minimize the TR app, etc.
All those almost require ERG mode use though. That is the guaranteed way to hit the power targets and duration intended. However, this could potentially be done with other trainer modes if the rider is familiar with the power target and/or intended effort, and they pay close attention to the audio tones that TR applies at the start and conclusion of each interval.
In short, it’s possible with the simple step of hiding or simple not looking at the screen in one or more ways shared above.