[hakre]

Not so sure if it "must" be _one_ config file.

I also don't think that the format matters more than it's use.

Reminds me of some good advice in The Pragmatic Programmer, should be (simple) text-files for editing and (regardless if one or multiple files), a single source of truth (e.g. if multiple files, not the same time the same data to edit in). This is roughly as I remember it and I found it always useful to apply.

If I see duplication, it's about fighting the rot and remove it.

If configuration files are generated, they don't belong under version control (there are some exclusions to this rule, e.g. pinning dependency versions for example when shared with the repository).