Is there any open source, embeddable alternatives or frameworks? I've got an ETL DSL that is fully serializable and I've been looking to create a UI tool for it.

I don't know of a solution for ETL DSL -> UI but https://github.com/lowdefy/lowdefy goes from a DSL to internal web apps. Perhaps some inspiration could be taken from there. Good luck!

Thats pretty fascinating stuff, thanks for the recommendation.

Maybe Airbyte if I understand what you're asking correctly.

Ah right. Yeah, reverse-engineering Airbyte's DSL and just "borrowing" their UI generation may be the move.