A lot of points on this thread are very valid.
However, in response to the OP's question, Apple 5W, 10W and 12W iPhone and iPad chargers with A-type US connectors
are certified for 115V/400Hz. There is a pretty good reason for that.
https://support.apple.com/en-us/HT202916 - this reference on Apple's site is dated 21 June 2017 but it has been around a lot longer than that.
However, before you go and plug one in, you would also need to comply with whatever EFB approvals are in place by your operator to be approved to use that power outlet for your EFB.