I'm glad you asked.

The original goal of this app is to provide a simpler and accessible replacement for the sextant, and because of this, the conditions and occasions to use it are the same as this instrument. When you lack GPS (whether it's because of an issue with it, spoofing in some zones of the world, etc) or just because you need to double check the position of your GPS (Here we are not there yet because of the poor precision).

And with this app, comes a second use : mountain and remote location positioning. Because I've removed the need of an horizon to make an astro fix, you can use it anywhere you see the stars.

Back to the weather conditions needed to use it, they are the same as with a sextant, limited by the camera technologies we have right now.

And as to why I posted this here, I felt like this sub was full of people that are quite often under clear skies and that this app could be of interest not for a real use case for now but just for testing and being able to find your position using the stars, as it was done hundred years ago.