Sorry, I took too long to answer this ahahhahaha Actually I didn’t know what I could answer because I’ve never thought about it before.
Today I watched all the cutscenes from 358/2 Days again (in HD from KH 1.5 omg it’s so perfect I cried like a baby, ok stop) and I think Roxas would understand how empty Nico feels, and vice-versa. I mean, Roxas is a nobody, he knows how emptiness feels like. I don’t know if they would be best friends, but I’m sure they could be friends.
Ok, I’ll stop talking now hahahahaha