Maybe it is just a matter of asking the users during the installation, if they want Assisted GPS or not? Users who really care about privacy would say no, and that is maybe acceptable. I mean, even without A-GPS, GPS still works. Sure, a fix is going to take 10+ minutes, but then you will have it, and you can keep it on all the time if you want. Also, services like the mozilla location service can help your device figures out where it is, without A-GPS. I don’t remember if it’s already available in /e/.