ansible_register_with_items

- hosts: localhost
  gather_facts: no
  tasks:
  - stat:
      path: >-
        {{item}}
    with_items:
    - /etc/FOO
    - /etc/hosts
    register: o
  - debug:
      msg: >
        {{ o.results
          | selectattr("stat.exists", "equalto", true)
          | map(attribute="item")
          | first
         }}