According to Jennifer Bailey, vice president of Apple Pay and Apple Wallet, a digital version of the U.S. passport will "soon" be available on iPhone.
the feature is coming soon
During her keynote at the Money20/20 USA conference, Bailey confirmed the upcoming feature. Apple's website states it will be available "later this year."
The update requirement for the feature is unclear, as Apple's website no longer mentions the need for a software update.
Author's summary: Apple iPhone to feature digital U.S. passport soon.