We had
visors like this installed in our aircraft and found they were invaluable when looking into the sun.
Rosen Visor
The ones we used were of very high optic quality and hard enough to resist scratching.
As an air traffic controller in San Diego, we were often looking into the sun for aircraft from the tower. We had high quality see-through roller shades that we'd pull down to unroll in the window. These provided a wide area of filtering in a flexible sun filtering film...kinda like flexible sunglasses on a roller shade.