You mean SQS FIFO? SQS classic cannot guarantee exactly-once delivery or ingestion, either due to failure at the client or server. SQS FIFO, however; can but requires both the client and the server to work in-tandem to ensure exactly-once processing.
How’s amazon’a kafka offering going?
It’s also what every lambda framework (serverless etc.) dumps you on by default. Often without any alternative being available.
But with ASP.NET Core it's effectively a Web API as a Lambda. It maps the event to a request and passes it through the asp.net framework as if it's a normal website.
The config for this is like 3 lines of code so if you don't want to host in a Lambda anymore, it's trivial to move to IIS, Windows Service, Linux.
X could be:
List prime numbers, List fibbonaci numbers, Conway GOL, etc
So you say Kinesis is bad for message streams where each message should be handled by only one machine? Well duh, that's how it works. Kinesis is meant for every listener to be assured to get the entire stream. It was never designed for that, and I expect you'll have a bad time if you try to use it that way. SQS is obviously what you want if you're interested in guarantees that each message is handled once and only once.
One Lambda per route in a decently-sized restful webapp is ugly and unmanageable? Well duh. Don't do that. Do pretty much anything else instead. Seriously, anything else at all.
This sounds more like, if you want to deploy services on AWS, do either pay somebody who knows what they're doing, or spend some time checking out the services to make sure they are designed for what you want. Don't just pick a random AWS service and usage pattern from a Google search and start building around it without ever checking if it matches what you're trying to do.