Headless Magento 2 Devs – how are you handling the checkout process?

I’m working on a headless Magento site with JS, heavy utilizing Redis for caching, along with the Magento 2 REST API.

How are you handling the checkout process? Are you doing some type of SSO? Do you send payments over the API, if so, how are you handling the PCI compliance?

Is there an extension or something to similar to stripe where it’s a “pop up” like template to submit the payment?

I’ve done some research and everyone talks about how to do headless but they always seem to leave out the tricky piece which is the checkout process. Thanks!