In English you could say I am FOR salmon though!

Isn't 난 just 나 (I) +‎ ㄴ (topic marker)? So it seems like 난 라면 should be translated more or less as "As for me, ramen" and 난 프랑스 as "As for me, France".

You are absolutely correct - I oversimplified. On the other hand, nobody says "As for me, ramen" in English (it's not even shorter than "I'll have ramen"), so there's that.

You could just say "Ramen", "Ramen for me", "I want ramen", or maybe even "Me, ramen". But I get your point - it's more common in English to use a longer sentence. The same thing is pointed out about Japanese too - "watashi wa ramen" for "As for me, ramen" - it has the same topic-comment structure as Korean.

I may want to add that as a person who had a lot of exposure to Korean (but is not native). Directly translating for instance “나는 라면” with the example context you mentioned, feels like „in my case, Ramen“. The 는/은 is describing the 나 in a way that is contrasting whatever was said in the current context. It is certainly used for saying something that is different from the other. „Well in MY case, it is …“, but it may work for other cases too, I am not totally sure.

English has one word answers for those questions.

It’s just conversationally dry and people will assume you’re not interested.