The primitive-recursive property of Cue (https://cuelang.org) is a big draw for me, and may be an alternative worth checking out. The authors have spent a great amount of attention to the type system (they learned a lot of lessons from previous config language designs that did not take lattice theory and unification into account).
The tl;dr is that inheritance is bad in config, whether it be from OOP or layering yaml files like Helm. The reason being that it is hard to understand where a value is coming from and where one must make an edit to correct it in high-stress SRE situations like downtime. Marcel worked on both major config languages at Google, and iirc Starlark is based on GCL ideas
