Of 18 SaaS products developed in a prior shop, only 1 used K8s (which was purchased as such). The former CTO was trying to push all of the others into 1 mega-cluster, including putting monoliths into containers, but the last I heard that effort failed.
We had a sprinkling of Lambda/serverless applications as well as Docker containers in EC2 instances.
I was developing a Terraform oriented platform to allow most developers to specify the values for module calls (without much Terraform knowledge) and the Sr developers & cloud team to work together to build those modules.
In my current job search, primarily for AWS/Cloud Architect jobs in local non-software companies (although with very large software footprints), I'm seeing mostly EC2, some serverless, some Docker, and mostly vague someday thoughts of K8s (but some of the jobs actually had some).
Around this Platform Engineering Slack it seems to mostly be K8s.