FYI, I can confirm that the ACR122U NFC reader works in cardpeek. And has native OSX support, too, so no more need to spin up a Windows VM to use my old HID NFC reader. ^ The downside is that I had to order that one from China, so it took a while to arrive.

Also, I noticed that Sprouts gave me a cashback prompt after tapping a debit card in Google Pay and entering its PIN. I wonder if that option actually works on contactless; might be worth a try. In any case, if you're going to try to route debit contactless transactions over something other than Visa or MC, their implementation is probably one of the better ones.

EDIT: looks like cashback does work over contactless at Sprouts. I wonder why I was thinking before that EMV contactless precludes it. Receipt: