Proceed to Checkout Button Link filter » proceedToCheckoutButtonLink

snippet.js

const { registerCheckoutFilters } = window.wc.blocksCheckout;

// Adjust the proceed to checkout button link.
registerCheckoutFilters( 'example-extension', {
  proceedToCheckoutButtonLink: ( value, extensions, { cart } ) => {
    if ( ! cart.items ) {
      return value;
    }

    const isSunglassesInCart = cart.items.some(
      ( item ) => item.name === 'Sunglasses'
    );

    // Return the default value if sunglasses is not in the cart.
    if ( ! isSunglassesInCart ) {
      return value;
    }

    return '/sunglasses-checkout';
  }
} );