If you have the desire to understand the individual components of running infrastructure for docker containers I'd suggest the full hashicorp stack.

Running nomad, vault, consul together isn't difficult, and will get you a better understanding how to deploy 12 factor apps with good secret storage and service discovery.

Add in Traefik for routing and you've got an equivalent stack to k8s, but you can actually understand what each piece is doing and scale each component as needed.

If you're going to run this all on AWS you can stick to just EC2 and not have to drown in documentation for each new abstraction AWS launches.

As an added bonus nomad can run far more things than just containers, so you have an on-ramp for your legacy apps.