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.
on android there is microG with the unified location modules. this is the part that can locate you by surrounding cell towers or wifi networks. you can use a third party database and save that to your device.
For the 'assisted' part: i think there are alternate download servers for the satellite data that is required for the A-... part. I don't know much about that, though. I believe they are incorporated into privacy oriented android versions like GrapheneOS or CalyxOS.