commerce-8.x-2.8/modules/payment/commerce_payment.links.action.yml

entity.commerce_payment.add_form:
  route_name: entity.commerce_payment.add_form
  title: 'Add payment'
  appears_on:
    - entity.commerce_payment.collection

entity.commerce_payment_gateway.add_form:
  route_name: entity.commerce_payment_gateway.add_form
  title: 'Add payment gateway'
  appears_on:
    - entity.commerce_payment_gateway.collection

entity.commerce_payment_method.add_form:
  route_name: entity.commerce_payment_method.add_form
  title: 'Add payment method'
  appears_on:
    - entity.commerce_payment_method.collection