I wouldn't equate the lambda UX with "serverless" at large. I work on a serverless system that runs the same code you upload (e.g, python). You write it as a traditional API then upload it to the cloud and done.
One thing that makes it possible is that "orchestration" is embedding in your code, using a library (https://github.com/dbos-inc/dbos-transact-py). With lambdas you need step functions which is not exactly easy to test locally.
There are a bunch of gotchas outside of UX, that make them just as awful. Like if you need secrets you have to find a way to cache them so that aws.secretsmanager doesn’t ding your bill every request. Depending on how your devops team requires you to load secrets this can make the code worse in operation and review.
But the main point why serverless is garbage is that the old stack does everything better.
One thing that makes it possible is that "orchestration" is embedding in your code, using a library (https://github.com/dbos-inc/dbos-transact-py). With lambdas you need step functions which is not exactly easy to test locally.
Also no need for "layers".