Many carriers & jurisdictions are looking at these "passports." They are a great idea in theory. But, in practice, they fail for lack of coordination and compromise.
Not sure that it is helpful to develop an app which works for LHR departures but not for other (at least major) stations around the world. Remember that we still have many jurisdictions which insist on paper visas or visas stamped into passports and, in fact, passport books themselves are vastly outdated and ought to be replaced by digital.
Maybe this is the start of something good, but it will take a long time and the advice will always be to have paper copies of everything in hand no matter what.