k3v runs as a dedicated virtual Kubernetes control plane. When pods are launched they are launched in another cluster.
Razee is an open-source project that was developed by IBM to automate and manage the deployment of Kubernetes resources across clusters, environments, and cloud providers, and to visualize deployment information for your resources so that you can monitor the rollout process and find deployment issues more quickly.
Cross-Cluster Network Connectivity for Kubernetes
Submariner enables direct networking between pods in different Kubernetes clusters on prem or in the cloud.
Kubernetes native multi-cluster canary or blue-green rollouts using Helm - bookingcom/shipper
Multicluster-controller is a Go library for building Kubernetes controllers that need to watch resources in multiple clusters. It uses the best parts of controller-runtime (the library powering kubebuilder and now operator-sdk) and replaces its API (the manager, controller, reconcile, and handler packages) to support multicluster operations.