Stupid question: how do civilian GPS units know that they're above 60,000' or faster than 1000 knots without, um, working?

Well, they work internally, just don't expose information to the outside.

I’ve managed to get a GPS lock while flying, it just takes a few minutes to find one. Was it misreporting my position? because it usually matched up with what I saw outside of the window

Probably because you were in a large aluminium tube at the time, and had no internet to get the AGPS data, so it had to receive the orbital elements from the satellites. (IIRC, this can take as many as 24 minutes worst case)

If you're using GNSS tracking on a flight, consider checking out the OSMand~ app for android. There's a map layout for flying, though I don't know if the navigation features work.

Civilian planes do not go 1000kts or up to 60,000'. Your phone GPS works fine in a plane as long as it can see enough satellites (pick a window seat).

Maybe they read 60,000 even when at 62,000?

I think the "and" in that sentence used to be implemented as an "or" in the days before everyone's phones had GPS in them. So you'd need to power cycle the device before it'd work again. Now most devices need to hit both limits at the same time before refusing to work.

Even now, it seems it may be up to interpretation. In searching for those numbers, I saw a post in a amateur high altitude balloon forum asking which modules were "or". (Presumably since it's a little more likely your balloon will exceed the altitude restriction and not the speed one.)

I have pictures from my camera (with location permissions enabled) that don't have any GPS data in it, or at least the data is extremely wrong.

I can't help diagnose that for you. There are other ways to get your current location, etc from your phone though.

I have GPS Test[1] on my Android - it's pretty neat to launch it while on a flight - seeing the speed in realtime is pretty fun.

[1] https://play.google.com/store/apps/details?id=com.chartcross...