Came across Dataland.io today.
It’s a bit like Ninox only with a GitOps approach to configuring entities, a more modern-looking UI (dark mode!) and much less powerful forms/editing panels. It’s backed by PostgreSQL internally, claims to implement row-level security, and has a programmable serverless worker model (TypeScript) for running custom actions when entities get updated.
It’s in closed beta (you can request access), but they have a pretty comprehensive video detailing how it all works. It’s certainly not a direct Fibery competitor, but it is in a sort-of overlapping space and some of it might be of interest to people here.