There are couple of good books to start with -

• Ash Framework: Create Declarative Elixir Web Apps by Rebecca Le and Zach Daniel
• https://devcarrots.com/

I have read the first one and it’s pretty good and covers lot of details and code examples building a full app.

However, I feel like none of the books cover some of the advanced concepts. For those, you will likely need to dig into Ash’s official documenation.

Hope this helps!

Personally I’ve just started building. Once you hit some roadblock you investigate and learn that way (the best free resource xD). Also if you don’t understand some Ash concept AI usually can explain it well - using AI to teach you things and not just implement things is imo underrated .
I guess this hands-on style doesn’t suite everyone and probably in the past it made my learning period much longer, but now with AI hitting some problem doesn’t mean that I have to spend 6h trying to understand it and instead I can rely on something that probably has my exact question in training set or can consume ash codebase at pace fast enough to give me the answer so this approach is more viable than ever.
EDIT. probably not the answer you wanted considering how the question is phrased, just wanted to say that it works

The official docs, as well as posting here on Elixir forum and on the Discord group.

That being said, if you value your time at all, pick up the Ash Framework book. It will save you untold hours. The learning curve is no joke.