Hi Antoine. Google Pay is available in The Netherlands. You can use it with both Maestro and Mastercard. What is not available in The Netherlands is the Google Pay app, but that is not needed to use Google Pay to pay with your cards.
You can find more information in this article: https://together.bunq.com/d/8681 and here: https://together.bunq.com/d/8480
Tap&Pay is indeed not supported anymore, so you won't be able to set it up this way and you will have to use Google Pay instead.