It seems that all the device manufacturers (they mention Apple, Samsung, and Google) are using BeiDou anyway. I don't know if that includes Garmin watches, though.

https://www.reuters.com/technology/us-agency-probes-risks-fo...

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rzzzt 3 hours ago | parent [-]

AGPS also helps if you have cell towers nearby.

	▲	askvictor an hour ago \| parent [-]
		This is only to make getting a fix faster - A-GPS downloads the almanac data via the internet (fast, but needs internet) instead of directly from the GPS satellites (slow but works everywhere). It doesn't make it any more accurate.