I missed the one directory part, I'd definitely recommend making that more flexible. With my equivalent of this I often mount multiple repositories into a single VM, two examples:

- a bunch of gitops repos: terraform mono repo, argocd-esk conf repo, grafana provisioning repo, etc.

- frontend + backend repo (tbh may merge these to a mono-repo, but here we are)

I think the auto detection is interesting, but tbh with my solution I've been happy with just install all the tools regardless of what a specific project needs - with a COW base layer this is cheap.