Switzerland Klausenpass

This is a nice location if you are looking for dark skies in Switzerland. During the night you won't have a lot of cars passing by - perfect for your astrophotography. There are a couple of places you can stop along the road and there is even a hotel nearby to get some warm meals or spend the night.
Of course, during the daytime, the view is spectacular too!

If you want to shoot the stars, you need a lens with a wide open aperture eg f1.8. for the Milky Way arch, I used a 20mm f1.8 and took about 12 images and stitched them together.
For more insight and information on night sky photography, you are welcome to visit my website: https://www.lonelylandscape.com/post/how-to-capture-shooting-stars

I think it is best to get there by car. There are a couple of places along the road to stop - also on the other side of the mountain. I believe that the road closes during winter. So get there during the summer!
Be aware that there can be a lot of cows in the region - be cautious during the night, these animals don't walk off the street when your car lights shine in their faces!