I like the idea and we use it at work often. One pitfall one has to be aware is that it is easy for the people who are asked to provide feedback on the prototyp

I like the idea and we use it at work often. One pitfall one has to be aware is that it is easy for the people who are asked to provide feedback on the prototype to get bogged down in the details. What you want is people to squint and tell you if they like the general approach, but what often happens is they tell you that you need more unit tests and you could use a ternary operator here and here. (The particular details will of course differ in each case.) The reason for that, in my opinion, is that your thing looks like a PR and therefore people default to the kind of review they do for PRs. But since this is a different beast it needs a different mindset during review. And of course the only possible solution for that is proactice and active communication to get everyone on the same page.