Heyo—this is a serious WIP right now and not ready for use.
I hope to release something more stable soonish. I am waiting for use-shopping-cart v3 to be released as well. If you want to follow along just check for the most recent active branch referencing stripe or usc.
As a side note the intention of this integration with Stripe and SANITY.io is to provide a very basic e-commerce platform. Ideal for someone who has only a few products or subscriptions to sell. If you need a more full featured e-commerce platform I would suggest a headless shopify or snipcart integration.