Assisted GNSS is pretty handy. My phones gets my approximate location very fast. If I want to plan a route from where I am, I don’t have to wait a couple minutes for the GNSS signal to be received (if I’m in a location where I can receive it).
But obviously, waiting a couple minutes before starting a journey is acceptable to avoid being tracked by Google, so I disabled the Enhanced Location mode on my Android phone.
Is there a private alternative for A-GNSS?
It depends on how good your phones gps is. My phone (Fairphone 4) has a pretty good gps antenna, and the time it takes for a gps lock is very similar with or without google location services. I turned off google enhanced location a long time ago and never looked back.