This is a pattern that was presented by Heitor Lessa at re:Invent 2019. The readme contains a link to the static slides and youtube recording.
API Gateway integrates directly with SNS without a Lambda in between, then there are 2 SQS consumers with message filtering applied to distribute the load.
This pattern is offered in Typescript/Python CDK versions and each has the vanilla CloudFormation (template.yml) included.
Clone the repo, deploy the pattern and learn today on cdkpatterns.com - https://github.com/cdk-patterns/serverless/blob/master/the-big-fan/README.md