Is there any available documentation or notes on the state file that Pulumi generates? I want to take a bunch of related state files and parse them to see if I can create some kind of diagram of dependencies and components.

I think the only documentation is the go docs: https://pkg.go.dev/github.com/pulumi/pulumi/sdk/v3@v3.101.1/go/common/apitype#DeploymentV3 It's not really intended as a public API but it is pretty stable. The format is very stable, but the Go code to deal with it does sometimes have break changes introduced to fix issues in the engine/make it easier for us to work with.

I'd start with https://www.pulumi.com/docs/cli/commands/pulumi_stack_graph/

Good pointers, thanks Fraser and Baz!