Defaults:
You can use one of any or all the available payment methods.
App environment:
Remember to set you app environment to sandbox or live accordingly when using PayPal.
Per block per product:
Each block is treated as a product on it's own and have a unique id associated with it. This makes it possible
to include multiple products in a single WordPress post, and any user can buy any of the product (s).
The Issue: Every time a block is duplicated, it's content (values) is too, this includes the unique Id (not unique after duplication), and will be an issue when a customer is accessing a post with multiple product blocks where same have the same unique id. They might have access to contents of the wrong block.
The fix: Every time you want to duplicate a block, don't, instead insert/add + a new one, as with that comes a new unique Id. (working on this to fix the duplicate unique ids.