I agree, he trusted the wrong people, yet again. I keep telling him employ the patriots.
All App development is non trivial and harder than most people think, it's not just about $, but time, tests, architectures, and a plethora of understanding. This site alone in not CM but 50 devs over 3 1/2 years, check the Git repo. Many 3rd party libraries not built in house either. IOS and Android are different code bases unless you use the Flutter/Dart framework.