ditto: "Are there satellites that take advantage of, or require constant availability of sunlight on the spacecraft itself, available in Sun-synchronous orbits?"
This question is an offshoot of this answer.
As a clarifying example of what "take advantage of... availability of sunlight" means as requested in comments, a satellite could, potentially, substantially reduce the volume and mass of its battery if it could take advantage of the constant availability of sunlight in a Sun-synchronous orbit. Depending on specifics, it might still require a small battery for backup of critical low-level functions. That's just a hypothetical example for clarification purposes.
A clarifying counterexample would be a satellite that takes advantage of the constant availability sunlight reaching the Earth's surface so that it can be photographed.