I can’t think of any. As a work around you could use a Firefox fork and have it set to always open new tabs in private tabs.

I have Fennec set up that way.

Yes, that’s my understanding. So it’s more work to use than point and shoot, which would be a nice feature for someone like me who can recognize major constellations and planets, but not much else.

Planisphere is alright, it’s basic, but does the job. No nasties in it and works offline.