Quick Buy Now Button for WooCommerce

Hi, I have just purchased your plugin which works so fine. However, in my website, there are two types of products. “Membership” & physical goods. I activated “Buy Now” function in my Membership. When someone clicks it mistakenly, and then adds some physical goods into the cart, they will have a chance of getting the unwanted Membership if not double check the list. So I would like to request for the feature if possible. Thank you.

The function can be found on extension called “Cashier->Preserve existing cart items on Buy Now”. https://woocommerce.com/document/cashier-for-woocommerce/
(I did the refund with Cashier due to unwanted conflict with some of my site builder)