While most customizations are handled through the PreProduct app, you can add special pre-order data-attributes to your PreProduct tagged buttons or snippet for custom functionality.
data-native-pre-order-btn
data-native-pre-order-btn="Pre-order me :)"
data-headless="true"
data-starting-variant="123"
data-cart-redirect-url="/fancy-thank-you-page"
data-native-cart-pre-order-cta-container
data-quick-pre-order
data-domain="mystore.myshopify.com"
data-primary-native-pre-order-btn
data-pre-order-quant="2"