What is Cloud Run, exactly?

Cloud Run is Google Cloud's solution to serverless container deployment and execution, and it's powered by Knative. It lets developers execute pre-built apps by converting a Docker (OCI) container image into a stateless, autoscaling HTTP service.
Cloud Run is a container-based development platform that enables you to run applications that serve numerous endpoints on a bigger scale and with fewer architectural constraints.
Cloud Run is a completely managed platform.