Somewhere someone wrote that he did send his librem5 (without batteries) to purism just to get it returned with batteries. He contacted support beforehand to arrange it.
About chinese batteries: Somewhere, I think it was a purism employee, stated, that those chinese offers are likely batteries, that didn’t pass the quality checks, and are therefore not safe for use. So its highly recommended not to buy or use them.
Lastly: Once I sumbled upon a service, that gave you an american adress, and than forwarded the goods to abroad destinations. Didn’t make use of any of such services yet and I cant tell if and how those handle goods like batteries.