I'm a big fan of Diátaxis and I'm using it to build documentation for Logdy: https://logdy.dev/docs/quick-start
I'm curious how people see it and whether it's a useful way to document a software product, feel free to leave a comment. So far it proved to be an effective way to communicate how to use the product also through a series of blog posts that present common use cases. Defininitely recommend!
I don't know if it's perfect, but I have yet to meet anything better. I discovered it late in my 20-year technical writing career, and it felt like meeting an old friend for the first time.