I am trying to wrap my head around outputs and stack references and using

.apply(lambda x: x)

with Pulumi/Python, but am having difficulty really understanding it. Is there a good white paper that explains it all clearly?

So there's a few resources for this: Firstly our main docs on Inputs and Outputs, https://www.pulumi.com/docs/intro/concepts/inputs-outputs/ But also me and @billowy-army-68599 have both wrote blogs about apply, Lee's is targeted at just about anyone, https://leebriggs.co.uk/blog/2021/05/09/pulumi-apply. While mine is if you've got an functional programming background, https://blog.ibasa.uk/programming/pulumi/2021/05/20/pulumi-apply-monad.html