It's purely personal, by reading "Features at a glance" there is the interpolation of Ruby that I really don't like, I prefer by far the f-strings of python. And I don't think I'll be using unless and until that much (aren't they also Ruby ?). Again that's just IMHO.
If I had more skills in writing parsers and tokenizers, that's probably a project I'd do.
Nice job !
In the long run it would probably nice with a switch or an environment variable to make the banner less intrusive.
The license file seems to be missing.