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 in Las Vegas, Bailey reiterated the upcoming release. Apple's website states that the feature, initially delayed, will be
coming later this year.
Author's summary: Apple announces upcoming digital U.S. passport feature on iPhone.