The AWS CLI is a tool set that lets you manage your AWS resources. The CLI comes in two versions which, at the time of this writing, are developed concurrently: version 1 and version 2.
Internally, the AWS CLIv1 and v2 are quite different. Version 2 pulls in AWS libraries--libraries which are used across the AWS SDK ecosystem--rather than reinventing the wheel when it comes to common tasks, such as talking to Amazon S3. Running AWS CLIv2 on your operating system of choice requires building and installing these common AWS libraries.
To make installation simple, I've created an OpenBSD port for CLIv2 and its dependencies. Instructions for installing the port are below.