so what do you guys recommend? Zeit claims Now is serverless. but how can that be true if you need to manage Docker? how is it going to do things like automatically scale my DB instances, share data between them, and make them globally available

Zeit Now is not made for databases. It can host Prisma server if you provide a DB that lives somewhere else, like GCP or AWS. If you want to try that, the Dockerfile for Prisma itself is rather simple: https://github.com/develomark/prisma-now

If you want a complete serverless environment with database, I guess heroku is the best choice

If you use the demo server, your database instance is already living in the prisma cloud. That means the only thing you have to concern yourself is deploying the node server and it basically one command with the zeit now cli.