If you want your users to be prompted to enter a number in the Credit Card field (instead of text input), you achieve this by updating the input of this field in the Payment Components template.
From:
HTML
<input type="text" name="num" class="flat" placeholder="{{'Card number' | t}}"
ng-model="credit_card.num" required/>
To:
HTML
<input type="text" name="num" class="flat" placeholder="{{'Card number' | t}}"
ng-model="credit_card.num" required inputmode="numeric" pattern="[0-9]*"/>