If I have a microk8s node or cluster, is it feasible to add it to a kubernetes cluster?
MicroK8s is kubernetes, so technically yes you can join a MicroK8s node (without the control plane) to an existing kubernetes cluster.
But it will not be that straight forward command like
I will recommend to follow the instructions of the kubernetes distribution that was used to create the cluster. Example, if you use kubeadm to create the cluster, i will follow kibeadm guide to add nodes. Not because it is not possible, but it will be easier.