I'm in Canada and just got my first house. After growing up in Europe, the first thing I want to do is install those European style external metal blinds that fully 100% black out the room to an absurd degree.
(not associated with company, but they were "Yoolax Motorized Cellular Shade" in "Blackout Pearl" on amazon, and you measure and order the shades in 1/4" increments)
They came with these L-shaped light-blocker things that attach down the sides of the window opening to block light from the side.
You can get a pretty dark room, but I also put a little black tape on the few remaining tiny cracks.
Edit: Thank you for the replies!
https://www.rolladenplanet.de/vorbaurollladen/rollladen-stan...