I'd put ALL the ones listed above: SQS, S3, KMS, DynamoDB, EC2, RDS, Redis in the required "core" services column, and also throw in IAM, SNS, and SecretsManager as well. Those are all table stakes imho.

I'm using all of the above in LocalStack today. Frankly, I don't believe this is as "impossible" a task as several in this thread are insinuating. It's the type of rote work you can delegate to AI to build these days, as observed in this OP.

Building a test suite to validate the state-transient mocks in question against the real deal is not difficult. Only annoyingly expensive (in time and money) if run often, which is exactly the problem they're solving.