Mirimir earns his Bitcoin, so there's no cash involved.
But no matter how you get the Bitcoin, you can get whatever degree of anonymity you want, by mixing it many times. You mix via Tor and nested VPN chains, with a different Whonix VM and mixing service for each mix.
you can buy bitcoin KYC free on bisq.network (but there is a premium). Very low risk of loss of funds. You can even use zelle which is supported by most banks.
Bitcoin ATMs definitely have surveillance cameras - if they don't, the area surrounding their location do. As far as I know there are only a handful of older Bitcoin ATM brands that don't have a camera and even the brand I'm thinking of Lamassu has added cameras in their later models.[1]
But no matter how you get the Bitcoin, you can get whatever degree of anonymity you want, by mixing it many times. You mix via Tor and nested VPN chains, with a different Whonix VM and mixing service for each mix.