Hi there and welcome to the community!
Live display can be configured. It can be scheduled at specific times. It is much more yellow than blue light filter. It is free.
I don’t know so I can’t tell. But I doubt it.
Personally? Privacy filter. But that’s up to each one of us to decide.
Check the two treads about both screen protectors, and the general one about both. You’ll find extensive feedback.
Disappointing privacy filter protective glass
Fairphone 3 blue light filter protective glass
Fairphone 3 official screen protectors
I recategorized ths topic in #discuss:fairphone-3 instead of Help.