If it's triggered by api gateway, then maybe. But with S3 or kinesis or especially dynamo there's a good bit of lock in.

What do you consider the lock in when using RDS? S3? EC2?

It’s easy enough to separate your event sources from your event destinations. Anything that can trigger lambda can also trigger SNS message that can call an API endpoint.

If I did want to move from AWS that’s the first thing I would do. Put an API end point in front of my business logic, change the event from triggering lambda to an SNS message and move my API off of AWS. Then slowly migrate everything else.

That's kind of a lot

All infrastructure migrations are “kind of a lot”.

People aren’t using the same frameworks and infrastructure they used 10 years ago.