Yup, those are my thoughts as well. Not to mention the shipping of the product to the US from a foreign country a lot of the time. That ship/plane/train wasn’t eco friendly that it came on. I try to buy made in the USA whenever possible.The growing of the bamboo may be more sustainable than other options but you might look at what is done to process it into thread.
I choose local stores over shipping whenever possible. I don't think it makes much difference sustainability unless the product is produced locally but I want to have an option of local later and I don't want Amazon to get more of a monopoly.