The fact that they have launched on Apple but not Google means...

The fact that they have launched on Apple but not Google means they are programming native code.

It's so difficult to maintain separate platforms. Say you have Web, Apple and Google that's three different sets of code with three different sets of problems. Every time you want to add a new feature you have to re-write the code in three different languages targeting three different platforms.

It would have made things a lot easier to write the app using React Native. React Native is a Javascript library that allows for the cross platform development using standard web development technologies. React Native is used at Facebook which coincidentally is where it was created. It is also used at AirBnB and Uber.