The paper commonly used for receipts is thermal paper, which doesn't usually have any wax in it. But it's still not recyclable due to the other chemicals in it.

Kivra and such are privately owned, and it seems foolish to trust them with all your data. One should use Min Myndighetspost as a digital mailbox for government-mails, and encourage places to have alternative options (Hemköp and Willys lets you see your receipts on their own websites for example)