The GPS satellites transmit an almanac, a (coarse) list of all satellite positions:
https://www.e-education.psu.edu/geog862/node/1739
That’s apparently crucial for a low “time to first fix” and, as I understand it, that’s where A-GPS comes into play: Downloading this information from the satellites takes about 12.5 minutes, but downloading it via the internet (A-GPS) is much faster.
So the question is: How long is this data valid for? It’s a bit hard to find information on this … It looks like it’s valid for several weeks:
https://flysight.ca/wiki/index.php/Almanac_and_ephemeris
If true, it would mean the situation is much less dramatic than I thought. 😅 I go on a walk every couple of days and that gives the device more than enough time to download an updated almanac. So, I guess I should be fine without A-GPS if I regularly use (standard) GPS for an hour or so. 🤔
We’ll see. This might take a couple of months to find out. 😂