How / does F-Droid compile Flutter apps without the proprietary Android SDK EULA?

I’m running into issues when trying to compile an apk from a Flutter project when using Ubuntu’s android-sdk package inherited from Debian. How does F-Droid build its Flutter apps? Do you rebuild the Android SDK, or do you agree to the Android SDK EULA?

Yes. The Android SDK used by F-Droid is not FOSS.