- "pretty sure the first generation were pure-analog circuits"

This Wikipedia entry isn't what I had in mind, but it describes an interesting analog mechanism,

- "For guidance systems based solely on star tracking, some sort of recording mechanism, typically a magnetic tape, was pre-recorded with a signal that represented the angle of the star over the period of a day. At launch, the tape was forwarded to the appropriate time.[2] During the flight, the signal on the tape was used to roughly position a telescope so it would point at the expected position of the star. At the telescope's focus was a photocell and some sort of signal-generator, typically a spinning disk known as a chopper. The chopper causes the image of the star to repeatedly appear and disappear on the photocell, producing a signal that was then smoothed to produce an alternating current output. The phase of that signal was compared to the one on the tape to produce a guidance signal.[2]"

https://en.wikipedia.org/wiki/Star_tracker

Reminds me of the "the distance between the rails of a railway are due to the width of Roman horse drawn carts" story.

I understand these still do incorporate celestial navigation.

Since GPS is quite likely going to be unavailable at the time of use.