I tried this. A very large company reached out and asked for a custom version of diffdiff.net. They asked what my hourly rate was, and (thinking along the lines of this article) I offered to do it for a flat rate instead.

They ghosted me!

In retrospect, a "very large company" didn't reach out, a relatively junior person at the company did. I should have worked within their constraints. (Or just not taken the job, which, I guess, is effectively what I did).