Yep, this works. I used the same setup to order a George Orwell book:-)

But whatever Plausible (analytics platform) uses to process credit cards doesn’t take Moon (some error, likely thinks it’s a fraud).

I just got it working on Plausible as well! I think Moon accepts any "billing address", but the pay gate checks it against your IP or something, because it first rejected when I randomly picked an address but then I used zip code based on my VPN, and it worked.