What are the biggest challenges for e-commerce sellers

Tracking customers. Where they come from, when they buy, their activity, etc.

Marketing. There is a lot of competition in this group, which means it is very difficult to stand out.

Owning customer data - many sellers sell on Amazon and Etsy. The ecommerce sellers do not own the customer relationship - the platforms do. This leaves them vulnerable. You should always own your own primary sales channels.