AWS Cognito is AWS's authentication managed service that integrates natively with API Gateway & Application Load Balancer. Users can sign up directly with Cognito, Sign In & Recover password.
We needed API Gateway to get automatic validation, but we use Application Load Balancer in front of our APIs instead of API Gateway.
We can write a custom User Provider that will receive a Cognito Token, validate it and then return an authenticatable object.
Once I finished the code, I had a working authentication process that could validate and parse AWS Cognito tokens and make them an Authenticatable user for me.