Spoiler for Latest Discovery short take episode.
How is the prime Directive used in Star Trek? As a writers tool to manufacture drama, lol. I can't think of an instance where it stopped anyone from doing anything. If anyone has an example of prime Directive being followed please share.
As for the last Discovery short take. If the Kelprians (?) Had seen ships only, using transporter might be a violation. The species take Saru's people aren't in Federation, so prime Directive doesn't apply to them. The idea that the federation is the galaxy's morality police is both unexplored in trek and a very disturbing idea. Flying telling everyone what is or isn't allowed sure seems culturally respectful, not really. It is a great way to make conflict however.