Depends on the size you want to tackle. Let's shoot for MIT licensed or similar, so we don't have to do the unethical thing.
ESLint or Webpack would probably be attempts that are decently sized for a challenge.
Cheerio would be a bit smaller.
Chalk is probably close to the absolute lower bound of what's even meaningful. (You'd likely just regenerate a package that size from scratch instead of wondering about compat)
It works. It is hooked up to Stripe. You can upload your package.json and receive a fully cleanroomed set of dependencies to use yourself. It is up to you to determine whether this is a compelling product or a warning to those who care about FOSS.
I do like this idea, more difficult to do without access to the original source code, and I think that this would be more "reverse engineering" rather than cleanrooming, as you don't have the same concerns about copyright violation if you're working from a binary.
I think the same copyright concerns apply when working with binaries, which is why clean-room reverse-engineering was invented in the first place. So that no disassembled/decompiled code could be copied into the newly created codebase.
It would be a combination of reverse engineering and clean rooming, assisted with FOSS tools and LLMs; run NSA Ghidra to decompile the binary, LLM-clean the output code, LLM-generate the clean-room spec, LLM-verify the clean-room spec is not copyright infringing, LLM-generate code from the clean-room spec.
