Including variables from multiple folders while prepending the folder names to the variable names

I'm trying to recursively import variables from folders with the following structure:

containers
|_ deluge
  |_ defaults
    |_ main.yml
  |_ tasks
    |_ main.yml
|_ jellyfin
  |_ defaults
    |_ main.yml
  |_ tasks
    |_ main.yml

Each folder has a default/main.yml file that looks like this:

---
container_name: deluge

port: 8112
homer_url: "http://{{ ansible_host }}:{{ port }}"

These variables have the same names across all folders.

I would like to import the homer_url variables into a playbook in the following form, so that I can address them by using homer_containers.deluge, homer_containers.jellyfin, and so on:

homer_containers {
   deluge: "http://myhost.com:8112"
   plex: "http://myhost.com:32400"
   jellyfin: "http://myhost.com:8096"
}

Here's how I'm trying to do it:

---
- name: Get a list of containers
  delegate_to: localhost
  become: no
  find:
    paths: 
      - "roles/containers"
    file_type: directory
    excludes: "homer"
    recurse: no
  register: containers

- name: Include all .json and .jsn files in vars/all and all nested directories (2.3)
  include_vars:
    dir: "{{ playbook_dir }}/{{ item.path }}/defaults"
    files_matching: main.yml
    name: "{{ item.path.split('/')[-1] }}"
  with_items: "{{ containers.files }}"
  no_log: true

- name: print out
  debug:
    var: deconz.homer_url

- name: Populate the dictionary
  set_fact:
    homer_containers: "{{ homer_containers | default({}) | combine ( { item.path.split('/')[-1] : vars[item.path.split('/')[-1] + '.homer_url'] } ) }}"
    cacheable: true
  with_items: "{{ containers.files }}"

- name: print out
  debug:
    var: homer_containers

However, Ansible fails to resolve the variable name into an actual variable:

TASK [containers/homer : print out] 
ok: [myhost] => {
    "deconz.homer_url": "http://myhost.com:8085"
}

TASK [containers/homer : Populate the dictionary]
fatal: [myhost]: FAILED! => {"msg": "The task includes an option with an undefined variable. 
The error was: 'dict object' has no attribute 'deconz.homer_url'}