New lookup_plugin for nested dictionary.
Based on subelements but it will keep the key.

The nested list can also be a list in stead of a dictionary, Then the item.1.0 contains 0, 1, 2 and item.1.1 contains the string value

Example:

- name: test
  action: debug msg="Device {{ item.0.0 }} with details: {{ item.0.1 }} has partition {{ item.1.0 }} with details: {{ item.1.1}}"
  with_nested_dict:
    - ansible_devices
    - partitions