How to access outputs/variables from CloudFormationCreateUpdateStackAction?

[entest-hai]

I want to access URL of an API Gateway after CloudFormation Deploy, and pass the URL to a CodeBuild action. Here is my deployment action

const deployPreProd =
      new aws_codepipeline_actions.CloudFormationCreateUpdateStackAction({
        actionName: "DeployPreProdApplication",
        templatePath: cdkBuildOutput.atPath("ApplicationStack.template.json"),
        stackName: "PreProductApplicationStack",
        adminPermissions: true,
        variablesNamespace: "PreProdVariables",
        outputFileName: "PreProdOutputs",
        output: preProdOutput,
      });

Then build action - I want to access the API URL and test it

 // build action
    const integtestBuildAction = new aws_codepipeline_actions.CodeBuildAction({
      environmentVariables: {
        SERVICE_URL: {
          **value: deployPreProd???, // how to access the API URL here?** 
        },
      },
      actionName: "IntegTest",
      project: integtestCodeBuild,
      input: sourceOutput,
    });