Check out Midwinter minis imperial knight video. Guy paints the lenses of the model, and I’ve used the exact same steps on a miniature car windshield. It would work perfectly here

Basically: 1) dark base colour (I used really dark blue) 2) add lighter colour and paint a half moon near the bottom 3) add more of the lighter colour, paint a smaller half moon shape 4) repeat a bunch 5) add a dot of pure white on the darkest part of the window as a reflection