some banks used to have (or still) their own nfc capable payment apps, those users with such a bank can use those if no other roadblock is encountered (not passing Safetynet or other checks). But increasingly banking apps rely on Google Pay for the nfc function it seems (I saw no comparison table on this yet).
Sometimes supermarket brands offer their own in-app payment solutions (saves them processing charges) to let you do mobile payments in their stores, so you can go grocery shopping at least and forget the physical wallet at home.
Apart from Paypal that is accepted at point-of-sale sometimes, there are also contenders in the mobile payment space per country that exist outside Google Pay. sadly this is highly fragmented still in the EU where I live.
Microg has an issue tracking errors on google-pay api-stubs at Contactless payments in store with /e/ phone - #2 by tcecyk - if it would implement any of those APIs those issues would get updated.