of-course, it's seemingly a card not present payment, because it's digital payments infra unless you keep a card reader present to convert it to, your processor via bank to complete txn.
yeah, it is different for all and a lot of things come into account payer can be anyone consumer or merchant, anyone who would like to do a txn.
I'm familiar with Venmo and Paypal, so I'd pick either of those just because they're known to me. I'm not opposed to Klarna, but I know nothing about it and so would avoid the learning curve and account creation if I had another option. I'd go with a card if I had to, but that's higher friction because I'd need to set up a temporary throwaway card to do that.