Veerle As long as the payment terminals of the merchant support normal contactless cards (EMV standard) and your type of card is accepted (for example Mastercard), then Apple Pay and Google Pay should also work just fine, regardless of there being support for it by domestic banks in that country or not.
Easy example: While Apple Pay is not supported in Turkey by any Turkish banks, you can still use your Dutch bunq cards through Apple Pay when you're visiting Turkey on holiday. In every store that accepts contactless Mastercard payments. You should probably still take your plastic cards with you, because not every merchant might have a terminal like this.