It’s not any more “operationally complex”. The fact that Docker containers include the OS doesn’t make it more complex to run.

My Docker file that I used to convert my Node/Express API that was running in lambda consisted of...

- setting environment variables (I had to do the same thing in my CF template for lambda)

- retrieving the Node Docker image (one line of code - I had to specify one line of code in my CF template with lambda to specify that is was using the Node runtime)

- copying the files from the directory to the container (as opposed to specifying the locsl path of the source code in the CF Template)

- Specifying the Docker Run command (as opposed to specifying the lambda handler).

- running “Docker build” as opposed to “CloudFormation package”.

How it does it is an implementation detail.

In fact, if you use lambda layers, it’s almost equivalent to building Docker images.