The next two lectures are from the AWS Certified DevOps course because they go over the newer CloudWatch Unified Agent.
They are standalone lectures that you can follow along with.
Remember, as you will learn, for custom metrics (such as RAM) and sending logs to CloudWatch, you just need
The CloudWatch Unified Agent
A configuration file for that Agent (either a file or from SSM)
An IAM role that allows your EC2 instance to perform the API calls to CloudWatch and possibly SSM
Happy learning!