
android_get_device_api_level is an API 24 API, whereas flutter supports down to API 21. We have other places in the engine that use this API but they're not on paths that work < 29. Even though the ndk API seems to work on older devices we should still probably not rely on it...
Flutter Engine
Setting up the Engine development environment
See here
gclient
bootstrap
Flutter engine uses gclient
to manage dependencies.
If you've already cloned the flutter repository: