Stolen from Nostr.
I just keep them open for natural light, if I could keep the view out but block the view in, I’d be in heaven.
Talk to some tinting companies. People only think of tinting for cars, but some places will do houses as well. I did reflective tinting on my entire house to block UV to prevent fade, and also help reduce heat a bit, but during the day it reflects sunlight and makes it near impossible to see inside.
Just be very careful what kind of tint. Tinting double pane windows wrong can crack them.