Here's a third pary implementation that I came across that implements the full spec:

https://forsaledns.net/

Hi, author of RFC 10023 here.

I appreciate the interesting discussion!

If you’d like to get a better understanding of the concept, have a look here: https://rfc10023.nl

The biggest use case today, at SIDN (the registry for the .nl ccTLD), is described here: https://github.com/SIDN/ForSale-RFC10023/blob/main/examples/...