The tricky part there is that it wouldn't work if you just sat there in a tight look dispatching http requests, any one of them timing out would, likely, trigger the deadline and make all subsequent http requests not happen.

So, alternatively, you could do something with DynamoDB event sources, where you have some sort of pub/sub table that your lambda functions listen on (basically a list of all the http requests that have to happen) - thus keeping a minimal 1 lambda dispatch per http request. The catch is you would need another system to manage that table (technically that system can be lambda itself).

Two important things, 1) I haven't used the dynamodb/lambda integration myself so be skeptical of my suggestion and 2) what I can say from our usage of the s3/lambda integration is that concurrency is not a problem with thousands of lambda dispatches/second being surprisingly quick to spin up.