Localize Shopping Results

Guys, I am building an international e-commerce app using MERN stack and React native

Whats the best way to localize results? So products not listed in US are not visible to US customers. And German users are not seeing American products. UNLESS they choose to see them from dropdown like eBay and Amazon

I have tried using cloud flare but didn't work.

Any feedback and ideas on this will be greatly appreciated.

Thank you