AWS SAM Deploy, how to find URL of API Gateway?

I just had time to answer properly. Having API Gateway definition:

Resources:
  ...
  ServerlessRestApi:
    Type: AWS::Serverless::Api
    DeletionPolicy: "Retain"
    Properties:
      StageName: Prod
  ...

you can output

Outputs:
  ProdDataEndpoint:
    Description: "API Prod stage endpoint"
    Value: !Sub "https://${ServerlessRestApi}.execute-api.${AWS::Region}.amazonaws.com/Prod/"

I have separate AWS::ApiGateway::RestApi and AWS::ApiGateway::Stage resources, so my Output looked a bit different, since I didn't/couldn't hard code the stage name:

Outputs:
  ProdEndpoint:
    Value: !Sub "https://${ApiGw}.execute-api.${AWS::Region}.amazonaws.com/${ApiGwStage}/"

Resources:
  ApiGw:
    Type: AWS::ApiGateway::RestApi
    Properties:
      Name: 'Serverless Ipsum #noServerNovember challenge'
      FailOnWarnings: true

  ApiGwDeployment:
    Type: AWS::ApiGateway::Deployment
    # Required -- see https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-resource-apigateway-deployment.html
    DependsOn: ApiGwMethod
    Properties:
      RestApiId: !Ref ApiGw

  ApiGwStage:
    Type: AWS::ApiGateway::Stage
    Properties:
      DeploymentId: !Ref ApiGwDeployment
      MethodSettings:
        - DataTraceEnabled: true
          HttpMethod: '*'
          LoggingLevel: INFO
          ResourcePath: '/*'
      RestApiId: !Ref ApiGw
      StageName: prod

  ApiGwResource:
    Type: AWS::ApiGateway::Resource
    Properties:
      RestApiId: !Ref ApiGw
      ParentId: !GetAtt ["ApiGw", "RootResourceId"]
      PathPart: "{proxy+}"

  ApiGwMethod:
    Type: AWS::ApiGateway::Method
    Properties:
      RestApiId: !Ref ApiGw
      ResourceId: !Ref ApiGwResource
      HttpMethod: ANY
      AuthorizationType: NONE
      Integration:
        Type: AWS_PROXY
        IntegrationHttpMethod: POST
        Uri: !Sub "arn:aws:apigateway:${AWS::Region}:lambda:path/2015-03-31/functions/${ServerlessIpsumFunction.Arn}/invocations"