Does GPS require an installed simcard?

[ryo]

I know the modem is also the GPS receiver and doesn't do much as a modem until a simcard is present, but does the GPS portion require one be installed too for the separate satellite positioning?

Let's take this logic:
Did you ever use a dedicated navigation system in a car (before they became build into cars)?
Did you need a SIM card to navigate?

I think you're getting 2 things mixed.
Maps are downloaded from the internet on the fly, which requires a SIM card (or a WiFi connection).
Car navigation devices download maps through a USB connection to a PC, so those things don't need internet.
Android and iOS both have an option to download maps in advance, so you don't need to waste data while travelling.
GPS connects to a satellite with or without SIM card.

Not sure how the Pinephone handles it, I never really had a reason to try it out yet.
I was in Kyoto with someone who has been there multiple times already, and I know all of Tokyo, Kawasaki, Chiba, Funabashi, and Saitama (the usual places I hang out at) and my own town from memory, I haven't been elsewhere since November.