I stumbled upon a seemingly trivial task:

How to spawn a kubernetes resource from within a pod?

All examples in the python kubernetes-client examples dir are only "read-only" examples. Nevertheless, I found that this is the most relevant one. How to get the API_KEY? Well, this SO thread help, and then the following answer as well - I only had to grant admin role binding instead of just view. Overall, to create it all was:

# sa.yaml
apiVersion: v1
kind: ServiceAccount
metadata:
  name: some-nice-name

followed by:

# creates the service account
$ kubectl create -f sa.yaml

# now grant the permissions
$ kubectl create clusterrolebinding some-nice-name-cluster-role --clusterrole=cluster-admin --serviceaccount=default:some-nice-name

then to find out the API_KEY:

kubectl describe secrets $(kubectl get secrets | grep pyxecutor | cut -f1 -d ' ')| grep "^token"|  cut -d':' -f 2

and then I could do:

# job.yaml
apiVersion: batch/v1
kind: Job
metadata:
  name: hey-world
spec:
  template:
    spec:
      containers:
      - name: hey-world
        image: alpine
        command: ["echo",  "hello"]

and then this works:

from kubernetes import client, utils
aToken = {{API_KEY_FROM_ABOVE}}
aConfiguration = client.Configuration()
aConfiguration.host = "https://{{URL_ADDRESS_of_your_cluster}}"
aConfiguration.verify_ssl = False
aConfiguration.api_key = {"authorization": "Bearer " + aToken}
aApiClient = client.ApiClient(aConfiguration)
k8s_api = utils.create_from_yaml(k8s_client, "job.yaml")

and tadaaa we have a deployment.