anyone guide me deploying Rancher UI high availability.

What you do there is install it to a high availability Kubernetes cluster with either a DNS name with A records for all your servers or a highly available load balancer to pass between.

As per my understanding, Rancher UI need to be installed in K8s as pods, so that we can have HA

Rancher is installed either in a Kubernetes cluster or in a docker container (which is meant to be "just to try it quick" and not for production). Pods are just part of the Kubernetes jargon, the Rancher install (which you'll likely use their Helm chart version) from the Rancher docs will handle all that.

Thank you so much Bill, i will give a try.

If you don't know what Kubernetes distro to use and you're aiming for a secure environment, try RKE2. If you're aiming for lower resource machines then that's what K3S is for. Those are both Rancher project Kubernetes distributions so they're also what the downstream clusters would naturally use (if not cloud) as well. So it'll keep what you learn more useful.

okay, will try both.