It looks like the reader becomes active on Clover Stations with the contactless built into the receipt printer without requiring the screen to change away from the itemized list first. I'm not sure if it became active the instant the transaction was totaled though or the system automatically assumes card after a second or two (the cashier walked away from the register just before I tried to tap).

Also, I tried using Google Pay with my Capital One debit card at the Capital One Cafe today and it kept declining. I ultimately paid with a different card. The card itself looked active in the Google Pay app but it very well could have deactivated itself somehow when I activated the contactless card. I'll need to attempt to readd the card and/or call Capital One to figure out what's going on.