Meaning of "AWS CLI directly interact with AWS services without going through a separate service like Workspaces"?

The statement you're referring to might be a bit confusing, but I can clarify it for you. The AWS CLI (Command Line Interface) is indeed a tool that allows direct interaction with AWS services through command-line commands, regardless of whether you're using Amazon WorkSpaces or not.

The phrase "without going through a separate service like Workspaces" is actually not entirely accurate in this context. The AWS CLI operates independently of Amazon WorkSpaces, and its functionality is not altered or mediated by WorkSpaces.

Amazon WorkSpaces is a managed, secure Desktop-as-a-Service (DaaS) solution. It provides users with a virtual desktop experience, but it doesn't change how the AWS CLI functions. Whether you're using the AWS CLI from a WorkSpace or from any other computer, it still directly interacts with AWS services using the AWS APIs.

The AWS CLI is designed to work consistently across different environments. It allows you to manage AWS services and resources directly, whether you're using it from a local machine, an EC2 instance, or a WorkSpace. The CLI communicates directly with AWS services using your configured credentials, regardless of where it's being run from.

In essence, Amazon WorkSpaces doesn't "do" anything to the AWS CLI. It's simply another environment from which you can use the CLI, much like you would use it from your local computer or any other AWS service. The CLI's direct interaction with AWS services remains the same, whether you're using WorkSpaces or not.
Sources
aws — AWS CLI 2.18.5 Command Reference
Welcome to the Amazon WorkSpaces API Reference - Amazon WorkSpaces Service
What is a CLI? - Command Line Interface Explained - AWS