Engagement? Yeah, maybe she was suggesting that. Though she breaks it off by saying later “instead of keeping the promise I made back then, take this medallion!”
What did Nabooru mean? Later when she awakens as a sage she says something like (this isn't a direct quote) “If only I would've known you'd become such a handsome man... I should have kepth the promise I made back then.”
I always assumed she meant to let him marry her, or just in general to...