somehow, the authors of this website neglect to even mention Nix. maybe that has something to do with the fact that this is a marketing page for the tool they named Nx (seriously?).
I was actually about to mention Nix in my post as well. Being a casual NixOS user myself I wonder if there is any kind of monorepo tooling based on Nix? Without ever having used Bazel myself I always thought of it as Nix-like.
We use josh[0] to let people clone "just in time" repos with the tooling needed for our setup[1]. We've also started a consultancy (tvl.su) that helps companies move onto this setup, and have customers going for it already.
The reasons we've not been making a lot of noise about this are that we have other large projects(like Tvix[2]) taking up time, and also the integration with customers moving to this setup lets us more confidently figure out what parts we need to smoothen for "non-TVL" use-cases.
As for using Nix in a Bazel-like way, the common experience with Nix is that language-specific build systems are wrapped. This being possible enables projects written in any language to be wrapped in Nix, and integrated in a Nix-based monorepo (something which makes it distinctly more powerful than other solutions).
However, there's nothing in principle preventing Nix from dropping down a layer to the project level itself, and we've implemented (and use) this for Go[3] and Common Lisp[4].
[0]: https://github.com/josh-project/josh
[1]: https://cs.tvl.fyi/depot/-/blob/views/kit/README.md
[2]: https://tvl.fyi/blog/rewriting-nix