All my questions were answered promptly and greatly by them, and I was getting more and more convinced to do it. Until I asked, "Stripe handles sales taxes, right?" and the answer was "no". They gave me a brief overview of how that works though. Let me tell you I know why you don't see an "Amazon of Japan", apparently in here I'd have to calculate the sales taxes for every country where my products are sold through agreements of Japan-{said country}. Some countries don't even have agreements like Brazil so they are in a gray area.
It seems like Stripe Tax might be a game changer for this specific situation! I'm not ready right now personally/professionally to try to do the company, but let's see in 6 months - 1 year. I am so jubilant!
PS, this is from a quick conversation I had ~1 year ago, so some small details might be fuzzy/outdated/incorrect. Ofc this is no legal or accountant or any kind of advice, just my experience.