Is there a name for open-top curtains?
I used to work for Lowes and I believe you’re referring to the cordless cellular shades that you can control from the top or bottom in order to maintain privacy and allow plenty of sunlight in as you mentioned, or you can put them all the way up from the bottom, and even play with color/ filter options. Not may drawbacks that I can remember. They are typically mounted inside the window frame, as long as your window allows for inside mount you should be good to go.