For Amazon AL2023 version, use dnf. DNF is the successor to YUM (from AL2).

https://docs.aws.amazon.com/linux/al2023/ug/package-management.html

To install python3:

sudo dnf install python3

Some images should have it already installed:

Package python3-3.9.16-1.amzn2023.0.9.aarch64 is already installed.
Dependencies resolved.
Nothing to do.
Complete!