One other “trick”.
You can get the ephemeris for a satellite - it will be valid for an hour or so (actually longer, but the satellite will go over the horizon and have to come back to be visible for it to be useful).
On the GPS Viewer it is called Get Ephemeris, which will save a log file.
There are binary commands to do the same thing.
If you then cold-start it, where it might normally take several minutes to get a fix, it should be able to do so within about 30 seconds.
Once a satellite has locked for a while, the ephemeris will be available and can be stored.
I don’t know the format of the AGPS file, but my guess would be that it is a compressed Ephemeris for all satellites.