Awesome product, btw. Definitely see where it fits some niches.
Actual concerns about running a real application with real uptime requirements.
1. Say your EC2 or docker container that's hosting this goes down. Is that left up to the user to deal with? RDS handles this for you
2. No ACID transactions if you ever outgrow a DB. You talk about in your pitch that the vertical scaling, so you have to just keep bumping the VPS/container memory.
3. Sure a SaaS application where a customer specific DB is isolated, but as soon as you hit any _real_ scaling limits you immediately are back to the entire problem statement you are aiming to (at least you hint at that in your pitch) solve which is the crazy n-tier architectures we have.
While I was being sarcastic, I was not being intellectually dishonest. There are entire hosts of problems that you call out you are trying to solve without providing any real solution.