This is great! After a brief glance, is there subscription functionality or is there a plan to add subscriptions?

I work at Stripe and built this demo, thanks for your interest! This sample StdLib app only showcases one-off payments, but subscriptions are easy to implement with Stripe: https://stripe.com/docs/billing/quickstart.

Check out Typographic, a demo app for subscriptions, that could be ported to serverless functions on StdLib too: https://github.com/stripe/stripe-billing-typographic.