Tinted plastic sheets provide shade
This is a hack taken from pilots. If the sun is bothering you and reduces the overall visibility, you can solve that problem by sticking pieces of tinted plastic sheets on your windshield or window.
You don’t have to glue it; the static on the glass will keep it in place. It will do the job as efficiently as any sun visor but at a fraction of the cost. Keep in mind that you shouldn’t place it directly in the line of sight.