Hey man, thanks for the question. I would love to hear your method of validating market need on e-commerce. I'm always learning!
1. Go to Amazon.
2. Choose a random product that interests you and click as far as you can get.
3. Check reviews and see what can easily be improved.
4. Check sales with 999 items in your basket-method (for at least one week).
Do this with several products.
5. Steady sales? Go source the product, check if it's profitable, import, sell, seek more products in the same business, import, sell.
6. If one answer is "no": repeat process.
Avoid stuff like products that everybody is selling, commodities, cool stuff, trends, electronics, grey zone stuff,...