I want my app to have two flavors: users' version and developers' version. Apparently, it is to be done with Flutter flavors.
I want developers' version to contain a "secret developers' key". How to ensure that users' version package does not contain secret developers' key (so, to make it impossible for a hacker to download it from Google Play and extract secret developers' key).
I use Android. In the future I also want to compile for iOS, and to be sure it won't contain the secret developers' key.
It is not possible. Consider everything in the app as public and open. You can make it harder to extract the "secret developers key", but it is not impossible.