One of the things I like about Mullvad is that I can buy a voucher on Amazon, and use that to pay for the service with a high degree of anonymity. Is/will something like that be possible with Uruky?

you can even mail cash in an envelope!

"Just put your cash and payment token (randomly generated on our website) in an envelope and send it to us. We accept the following currencies: EUR, USD, GBP, SEK, NOK, CHF, CAD, AUD, NZD."

I’m not aware of this, can you clarify? Technically anyone can top up an account on Uruky and give it away to someone else.

Like so, hopefully the link works for you:

https://amzn.eu/d/00yFWx41

The card arrives with a little lottery-ticket style scratchpad with I believe a 16 digit activation code underneath.

Thanks, I see. You're still giving Amazon and Mullvad your payment information, so unless you're purchasing it for someone else, I'm failing to see the advantage? Again, that's something you can already do with Uruky as well.

The advantage is that it makes it impossible for Mullvad or Amazon to associate my online payment with the activation code on the card, and by extension my Mullvad account.