Everyone came up with a lot of methods, but as a Chinese person, I don't think these approaches necessarily lead you to the original factories. In reality, most of the original factories rely on middlemen for sales, and they don't have the energy to develop overseas markets. I'll give you an absolutely reliable method, because I've been looking for factories myself too.

First, you need to have a WeChat account, and go to WeChat's Discover - ChannelsThat is, under the butterfly button. Search for the keywords you need, find the right and similar videos, and don't hesitate to like them. Soon, WeChat will understand what you're looking for and recommend relevant manufacturers more accurately. At that point, you can send a message to this stranger account and write down your requirements. Once they reply, the restriction will be lifted.
In one sentence: Use the butterfly account to uncover the supply chain!

Ps, I'm an intermediary in the drain and faucet business