Well, it depends on the specific comic series and storyline. In some, Namor acquires or uses vibranium for his purposes, while in others, it might not be a factor at all.
Namor has had encounters with vibranium in the comics. However, the extent and nature of this interaction can vary depending on the specific comic series and storyline.
He would probably be curious. Naruto is always eager to explore new things. He'd touch it, try to break it with his strength, and when he fails, he'd be even more intrigued.