CashApp as a direct on-ramp (ie buying Bitcoin within the app) would be your kyc method.

You can also use CashApp (or Strike, Revolut, Zelle, etc.) as a way to send money to another individual, as your payment method for them to transfer you some sats p2p.

The reason for spreading out your payment method is to reduce the centralized records of cash transfers. From a privacy perspective, if you’re frequently sending money p2p like this, especially if the receiving end is a “known” sats seller, one could make inferences about your stacking habits.

Hope this helps!