You need a bank account with Paypal still. This is direct payment into your personal virtual wallet (supposedly not linked to your real identity) avoiding all banks.
All of that will be tied to a real identity, but I am not sure Libra will also be completely free of these ties. There must be a point where to use your wallet you’ll have to justify your identity (i.e. above some amount or some kind of purchases you hit KYC requirements)