My thoughts EXACTLY. The great power in "serverless" architecture (i.e. AWS Lambda + AWS RDS + AWS Gateway) is how it empowers prototyping a new product.
Counterintuitively, it's future-proofing. You should know in advance that it's too slow & expensive. But you get to spin up a prototype backend very rapidly, pay only for what you're using while prototyping, and Lambda's inherent limitations force devs to build modularly, start simple, & stay focused on the product's main goals.
When the time comes to need scale, either at launch or even later when user count goes up, your "serverless" backend can be relatively easily replaced with servers. Then, just like that, in response to scale need your product's costs and response time go down instead of up.
It's a nice way to build a software product: rapid prototyping plus easy future cost decreases built-in.