Have you considered extracting the lambda portion into a lambda extension so that you can deploy this as part of any cdk/cloudformation stack or standalone lambda and toggle on/off local debugging based on some registration in dynamo (e.g. store a predicate applied to the event and proxy to local if the predicate evaluates true)? This would allow something like this to be hugely useful in mitigating outages.
I didn't catch it in the repo yet but I'd you're proxying local AWS calls through the lambda to allow quickly catching IAM and security group/routing issues, that would be incredible.
Happy to help with this stuff and will definitely be a user!