I couldnt find an easy way to implement the JS PayPal quick button so I just used the API and created my own buttons. Maybe this tutorial will help?
Here is a simple implementation of the PayPal subscription functionality in a Dash App. Maybe it can be of some use? I use the Python paypal checkout SDK, but write two classes to use the subscription api. Then I implement a subscribe button that redirects the user through paypal to complete the transaction. Once logged back in, the user sees the subscriber view.