I have a question about international sale of vape products

So I live in the USA, and I have friends in Europe who started their own vape brand which is in production right now. They would like me to be their US distributor. They want to do everything completely legal. What are the steps I need to take here to be able to sell the product to smoke shops? Is it possible to sell it online through a webshop? Can I sell it directly to smoke shops? If anyone is familiar with the situation, I would appreciate the help