I hope this doesn't come off as snarky, but after researching Vercel and its competitors I decided that the iffiness around billing for these services wasn't worth it. I would mostly use it as Infrastructure as a Service anyway. It took me about a night to learn the ins and outs of AWS CloudFormation. Now I know exactly what my stack looks like and I can more easily estimate my end-of-month costs -- plus I can stay in the free tier wherever possible.