The only related positive I think you should focus on in your interview/ application is conveying that your goal to serve, and that you are exploring multiple options available to achieve that goal if that is true (in your case sounds like it is). For other candidates who only want to serve in ROTC or academies and not the other, I saw no penalty for being honest about this - my DS was recruited by one of the academies but held firm and stated he did not want to attend an academy and received 4 year/ national scholarships from A, AF and N ROTC.
Just my opinion but imo no it's not more impressive that you received a congressional nomination to serve potentially through an academy to the ROTC committee. Let me try an analogy - Imagine you are courting a nice young lady, Susie, and mention to Susie that her uncle Bob just put in a good word to her sister Joann for you, who you also find attractive. if you were Susie, would this be a positive, neutral, or negative detail to become aware of? Would you be like "wow, nice, I better jump on this - now I'm smelling what the rock is cooking?" or a little put off. I don't know - but I wouldn't wave it in her/ the ROTC committee's face thinking it was a positive - again except to reinforce that you're applying because you really want to serve.
Opinions will vary I think on this but you asked so I'll share mine.
Good luck and thanks for your willingness to serve