I've never seen anything like that. I was able to request a refund, and I did, but it was denied. I then contacted support with no luck there either. Maybe you have consumer protections I don't in your country?

Nevertheless, why on earth would it allow the purchase to happen when it was set to deliver to a specific unsupported kindle, my only one? It just makes no sense other than as a scam.

FWIW a few years ago I found the my-country-Amazon is not another-country-Amazon. I had a problem with a phone after 6-12 months and they just sent me a replacement. A similar thing happened a couple of years later, I contacted support like at 1am from another European country and apparently I was sent to Amazon US support, which were useless... On the way back to the UK (still in the EU), I contacted support again (at a normal time) and this time they gave me a refund.