I'm a introvert and hate dealing with people, but for some reason I don't like using the self-checkout. I don't know why. But anyway, I recommend moving to Finland. My interactions are as follows:

A very quick eye contact with a nod as a hello.

I pay, receive the change, say thank you.

I go away.

There is no small talk or push for registering for their bonus card systems, etc, here. You go in, do your thing, say thank you, go away. And saying anything is optional. I do it because I feel like that's the least I can do for the poor person who has to deal with humans all day. But often I see people not even look at the checkout person, just stare at the register until it gives out a number, pay and bugger off.