configmap.yaml

apiVersion: v1
data:
  authorized_keys: |
    ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAID9Zt/CR+kt1omLPJmMLCJu1w3aIpg7IO0Vv7up+MVFI jp@hex
kind: ConfigMap
metadata:
  name: shpod

pod.yaml

apiVersion: v1
kind: Pod
metadata:
  name: shpod
  labels:
    app: shpod
spec:
  volumes:
  - name: home
    persistentVolumeClaim:
      claimName: shpod
  - name: pubkey
    configMap:
      name: shpod
  containers:
  - name: sshd
    image: alpine
    volumeMounts:
    - name: home
      mountPath: /home
    - name: pubkey
      mountPath: /home/user/.ssh
    command:
    - sh
    - -c
    - |
      set -e
      apk add openssh
      ssh-keygen -t rsa -f /etc/ssh/ssh_host_rsa_key -N ""
      echo "StrictModes no" >> /etc/ssh/sshd_config
      echo "group:x:1000:" >> /etc/group
      echo "user:x:1000:1000::/home/user:/bin/sh" >> /etc/passwd
      mkdir -p /home/user
      chown user /home/user
      exec /usr/sbin/sshd -D -e

pvc.yaml

kind: PersistentVolumeClaim
apiVersion: v1
metadata:
  name: shpod
spec:
  accessModes:
  - ReadWriteOnce
  resources:
    requests:
      storage: 1G

service.yaml

apiVersion: v1
kind: Service
metadata:
  name: shpod
spec:
  ports:
  - name: ssh
    port: 22
    protocol: TCP
    targetPort: 22
  selector:
    app: shpod
  type: ClusterIP

Fixed the connectivity issue with

sudo kubectl port-forward --address 0.0.0.0 service/shpod 2222:22