Blinds can be very private, if you close them. I have vertical blinds, not for privacy, but to keep the sun out. I have a couple of small side windows which are over looked and have stuck a clear pattern film over them, to avoid the need for curatains.
I have used Venetians but they do block a little light.
You could follow up the cafe curtain idea by making screens out of lattice pattern mdf. A friend did that when her kitchen window was overlooked (second floor) She could see out when she stood at the sink but from outside it blocked the view of the living area.
Cafe curtains are hung on a rod that is placed (about) half way up the window. The rod is a narrow one, usually brass, around half-inch diameter. The curtains may be on tabs. They are placed so that idlers passing by cannot see the faces of people seated at tables. The customers have a feeling of privacy but can see the sky, trees, buildings so they do not feel enclosed.
A restaurant may open them at times to entice customers in, or (especially in the mornings) close them to hide the fact that it is empty or cleaning is in progress.
They may be used in houses facing the street, and especially in bathrooms where the user can look out over them, but viewers cannot see the repellent silhouette of a naked body.
Depending on the degree of privacy required , they may be solid or net. In kitchens and tearooms a light, unlined, washable cotton may be used.