Ask HN: Experiences with low-code Open Source Dev tools?

In the past year or so there's been a lot of new "Open Source" low-code dev tools (similar to Retool) projects. So many that it makes it a bit difficult to commit to one.

There is a good page to track general adoption using Github Stars as a proxy: https://ossinsight.io/collections/low-code-development-tool/

But I am interested in reading experiences of real people using these alternatives. In particularly:

- What were the technical "gotchas" of the platform?

- Really Open Source vs Open Core? And in particular Licensing (AGPL or other risky licenses)

- How easy was the ramp-up?

- How "mature" did they feel? ready for production?

- Any "killer feature" ?

- If the project is Open Core, how does the flow to the paid option looked like to you? is it a smooth curve, or is it a very deep pricing step.