Maybe my answer is entirely UK based, but I'm pretty sure if I asked in my circle of non tech friends, I don't think any of them would have a concern about buying anything legal on a credit or debit card. You might not want your friends to know, but I don't think they care in the slightest about the bank or CC company knowing. And even if they did, that can be obfuscated a little more by buying it with a non-high street bank (like Revolut) they never have to go into/use for their mortgage or whatever.