Hi folks,
Circling back to this: I finally landed Bug 1419581, which added a --without-google-play-services configure flag and a continuous integration job (labelled BnoGPS, like this job to prevent us regressing the build parts at least. (There’s no test that verifies that the produced artifacts don’t reference Google Play Services in some way, mostly 'cuz that’s a hard problem.)
These jobs without Google Play Services are not shipped to end users, nor are they signed for release, so they’re not directly usable by F-Droid consumers. But hopefully this will let F-Droid simplify its build script (starting with Firefox for Android 60), and help keep F-Droid’s own builds green in the future!
Yours,
Nick Alexander