Ask HN: Would You Use a Declarative Back End (APIs, DB, Auth, Sync)?

I'm exploring the idea of building a developer tool/platform that allows you to define an entire backend (database, APIs, authentication, security rules, sync, etc.) purely through YAML files.

It’s somewhat inspired by Hasura DDN, where you can declaratively design your GraphQL layer. My vision goes further: you'd define everything in a backend/ folder using YAML — including:

Database schema: tables, relationships, constraints

Access/security rules

API channels: exposed through HTTP or MQTT

Functions: written in Dart (AoT compiled) or JavaScript

Auth setup: API keys, OAuth, JWT, etc.

Sync logic: so mobile apps can go offline and sync later

CI/CD friendly: entire backend versioned and deployed as code

This means a complete backend (DB + APIs + logic) could be spun up and deployed from source — no clicking around dashboards, just config and code.

I'm especially interested in making it work well for mobile developers (e.g. Flutter devs) who need offline-first backends or sync capabilities out of the box.

I’d love your thoughts:

Would this replace anything you’re using today?

What are the must-have features for you?

Any dealbreakers?

Too much abstraction or just right?

Thanks in advance — I'm trying to gauge if there's real demand here before going deeper. Honest feedback (especially critical) is welcome.