I'm wondering how phones accomplish the equivalent of an IRU alignment. And how frequently they have to realign due to drift.
Over a short time a phone or touchpad might work well as an attitude indicator. Assuming that in the event of an emergency (loss of primary instruments), when you pick it up it knows which way is up.
I'm guessing that phones might perform some sort of alignment when left sitting motionless for a period of time. Which can be determined by its accelerometers.