If people actually read the original paper by Royce 1970 they would see that it's an iterative process with short feedback-loops.
The bad rep comes from (defense|gov.) contracting, where PRDs where connected to money and CR were expensive, see http://www.bawiki.com/wiki/Waterfall.html for better details.
What solved some of my problems was a Firefox plugin called MarkDownload. Instead of saving a bookmark, just download the thing (as a text file) which makes it easier to find by search (or just grep -R).
The live site has a blogging feature: Title, Text, Picture. Once I'll get to it, it'll be added to the demo site.
Comments is just the text aspect. So it's already working!
The question here though: in a low-trust environment, i.e. the public internet, what do you do with API key for your GitHub Actions/CI pipeline. Can they be narrow enough to be considered public? Can you get rid of the Cloudflare Workers?