This won’t work - you’ll just get an error message.
Prepaid cards like Revolut also don’t seem to work (on Google Pay anyway).
I have used Curve with attached credit card to top up Dozens just fine with no problems. The app actually stores your card number too, so it’s even easier than Google Pay - fewer steps.
If you don’t have Curve, dm me for a referral code. Though use Curve at your own risk…
On a side note, the UI is a bit odd, in that you have to manually select your card each time, even though it looks like the card you last used is already selected.
Also, it seems that you can only add max £250 per top up, but then you can top up multiple times per day - not sure about the max number.
This has to be costing dozens quite a lot of money, so I’m expecting them to follow in the footsteps of Monzo, starling etc and put stricter limits on topups in the future.