it could mean he smells like sweat and hot skin, but he didn't say he stunk, so i think the author meant it in the way people loosely associate things. like sunshine could be associated with clean, fresh air, the smell of certain plants, maybe some light food fragrances like vanilla, lemon, or coconut. maybe even a type of laundry soap from people doing the wash and hanging their clothes out to dry, the smell of seawater or the beach, light stuff like that. associations that read "the love of my life" kinda shit.

"smells like sunshine" wtf a sunshine smell like