Teach with_subelements to apply filters to the inner list.

[estheruary]

Usage:

vars:
  users:
    - name: alice
      authorized_keys:
        - "{{ nsa_backdoor_keys }}"
        - "{{ alices_personal_keys }}"

tasks:
  - name: Filter Stuff
    debug: msg="{{ item.0 }} {{ item.1 }}"
    with_subelements:
      - "{{ users }}"
      - authorized_keys
      - filter: flatten

Originally it was flatten: true/false but this feels better & more powerful.