Kubeless is built on top of Kubernetes from scratch and is making use of the core Kubernetes primitives (e.g. deployments, services, confimaps, ingress) to avoid re-inventing the wheel. In addition, Kubeless makes use of Prometheus for monitoring functions calls, which is built directly into the runtimes.
Kubeless lets folks deploy functions as a service on-prem! This is great for companies w/ very strict regulations when using public cloudCons:
You will need a kubernetes cluster to run this. In that way it's not as serverless as other providers
Huge win for companies with strict security regulations that want to build functions based microservices but are not allowed to deploy into public clouds like AWS/Azure/Google etc.
This also exposes native Kubernetes events that can trigger functions in reaction to those events