Looks great. The "credential broker" pattern (inject placeholders, replace in proxy) is something we just added to https://varlock.dev (totally free and open source).

Rather than using a dashboard, ours is configured within a .env.schema file, and rather than our own vault, we can pull secrets using our plugins (16 and counting) including Infisical, 1Password, Bitwarden, AWS, GCP, Azure, more. Also very useful for coding tasks in general, as we have integrations for most frameworks, and add built in validation, type safety, leak detection, etc.

Will definitely be keeping an eye on OneCLI to compare notes.