Haha, this.
The U-2 and SR-71 had an old but great Astro-tracker. We flew it on missions that went way north, where there was always overcast (which precluded doing a ground fix update), and before GPS was really integrated into military flying ops.
I believe it was maintained by Northrop.
IIRC, it tracked 300 stars and gave us around 700' of accuracy. I had an engineer tell me a few years ago that 700' is terrible, compared to modern standards.
Unfortunately, airline certification for an Astro-tracker will take decades and cost millions of lives. Too bad. Works great, lasts long time.