Apparently you don’t need the physical card (or use it once / activate it) to use the virtual card in Google Pay. All I had to do, was enable Contactless in security, then it works!
I haven’t received my physical card yet, but have made several payments in different stores.
But I’m having issues with the top-up limit - the Revolut app doesn’t want to tell me what it is, and apparently there’s a daily limit. That might be a problem for me, since I can’t make a bank transfer to the account (my netbanking / mobile bank apps do not allow for SWIFT/IBAN codes), so the only way for me to top-up the card is by using the top-up button…
I do have to unlock my phone (using fingerprint), before paying with Google Pay - but I guess it’s how it works