If you're looking for a CIAM solution, then Amazon Cognito is definitely worth a try. To get started quickly with Cognito user pools, user sign-up, sign-in, password recovery, plus an extra layer of security through PKCE, I wrote a basic guide.
Cognito is surprisingly cost-effective. An estimate for 10,000 MAUs (monthly active users) can be as low as 0.015 per user per month. Not bad for a robust, secure, full-featured CIAM solution based on open standards.
If you plan to work with managed Kubernetes clusters, I wrote an eksctl guide to get started. It's an introduction to a command-line tool that automates K8s cluster creation in AWS. The guide takes you through the cloud infrastructure put in place through the tool, following a simple use case: create a cluster from a single command, without a config file.
If you're really into free, open-source load balancers, then you might enjoy a short guide I wrote for getting started with HAProxy. Set it up at your own pace on your local workstation to get a feel for making HAProxy work in a basic way.
Even after all these years, HAProxy continues to be regarded as a leading standard in software load balancing.