Bathroom window (looking outside yes / looking inside no)

why? That is precisely the great advantage of a blind compared to a simple roller blind

It makes no difference to me whether it's a roller blind or blinds. For me, it's not practical. Whether the roller blind is down when I get into the tub and up again when I'm lying in it, or with blinds, the slats are closed when getting in and opened again when lying inside, it makes no difference to me. Then I would rather switch to liquid crystal windows. But that's not practical for me either.

Depending on the angle, you can still look out without anyone being able to look in, that is already a small difference.

Switchable glass film might be something for you. Power on = view outside while bathing, power off = frosted glass effect ...

It's basically the same function as liquid crystal glass. But somehow it's not practical for me if I have to press a switch every time. If you can easily look into the window like that, the view isn't that great either (pure assumption without knowing the actual situation). Then I would rather lean towards a skylight above the bathtub, maybe also a panoramic skylight like (I think) climbee has.

So whether you completely darken a window with a roller blind or only make it harder to see inside with a [Jalousie] is already a huge difference.
([auch generell ist eine Jalousie dem Rollo in fast allen Belangen überlegen])