You are probably best off using a flat text file for this as Ansible can't natively parse Excel files. A very basic (can't guarantee to work) example of using JSON for this would be
Ansible Tasks:
# If the JSON file is on your Windows box
- name: read remote file
slurp:
src: C:\json_file.txt
register: reg_changes_raw
- name: convert raw slurp to json object
set_fact:
reg_changed: "{{ reg_changes_raw | b64decode | from_json }}"
# If the JSON file in on your Ansible host
- name: read local file
set_fact:
reg_changes: "{{ lookup(file, 'json_file.json') | from_json }}"
# Loop through JSON for win_regedit
- name: win_regedit tasks
win_regedit:
path: "{{item.path}}"
data: "{{item.data}}"
with_items: "{{reg_changes}}"
How you implement this is up to you but if it is the same reg keys you need to update and it changes only sporadically you should probably just stick with using the group_vars instead of dealing with external files