(1) This is awesome. Feels like this wraps enough complexity that it won't just be a toy / for prototyping.

(2) When a schema is provided, is it fully enforced? Is there a way to do migrations?

Migrations are the only remaining challenge I can think of that could screw up this tool long-term unless a good approach gets baked in early. (They're critically important + very often done poorly or not supported.) When you're dealing with a lot of data in a production app, definitely want some means of making schema changes in a safe way. Also important for devex when working on a project with multiple people — need a way to sync migrations across developers.

Stuff like scalability — not worried about that — this tool seems fundamentally possible to scale and your team is smart :) Migrations though... hope you focus on it early if you haven't yet!