Ansible, module_defaults and package module - ansible

Question

So I'm trying to write roles and plays for our environment that are as OS agnostic as possible.
We use RHEL, Debian, Gentoo, and FreeBSD.
Gentoo needs getbinpkg, which I can make the default for all calls to community.general.portage with module_defaults.
But I can, and do, install some packages on the other 3 systems by setting variables and just calling package.
Both of the following plays work for Gentoo, but both fail on Debian etc due to the unknown option getbinpkg in the first example and trying to specifically use portage on systems that don't have portage in the second example.
- hosts: localhost
module_defaults:
package:
getbinpkg: yes
tasks:
- package:
name: {{ packages }}
- hosts: localhost
module_defaults:
community.general.portage:
getbinpkg: yes
tasks:
- community.general.portage:
name: {{ packages }}
Is there any way to pass module_defaults "through" the package module to the portage module?
I did try when on module_defaults to restrict setting the defaults, interestingly it was completely ignored.
- hosts: localhost
module_defaults:
package:
getbinpkg: yes
when: ansible_facts['distribution'] == 'Gentoo'
tasks:
- package:
name: {{ packages }}
I really don't want to mess with EMERGE_DEFAULT_OPTS.

Answer 1

Q: "How to load distribution-specific module defaults?"
Update
Unfortunately, the solution described below doesn't work anymore. For some reason, the keys of the dictionary module_defaults must be static. The play below fails with the error
ERROR! The field 'module_defaults' is supposed to be a dictionary or list of dictionaries, the keys of which must be static action, module, or group names. Only the values may contain templates. For example: {'ping': "{{ ping_defaults }}"}
See details, workaround, and solution.
A: The variable ansible_distribution, and other setup facts, are not available when a playbook starts. You can see the first task in a playbook "Gathering Facts" when not disabled. The solution is to collect the facts and declare a dictionary with module defaults in the first play, and use them in the rest of the playbook. For example
shell> cat pb.yml
- hosts: test_01
gather_subset: min
tasks:
- debug:
var: ansible_distribution
- set_fact:
my_module_defaults:
Ubuntu:
debug:
msg: "Ubuntu"
FreeBSD:
debug:
msg: "FreeBSD"
- hosts: test_01
gather_facts: false
module_defaults: "{{ my_module_defaults[ansible_distribution] }}"
tasks:
- debug:
gives
shell> ansible-playbook pb.yml
PLAY [test_01] ****
TASK [Gathering Facts] ****
ok: [test_01]
TASK [debug] ****
ok: [test_01] =>
ansible_distribution: FreeBSD
TASK [set_fact] ****
ok: [test_01]
PLAY [test_01] ****
TASK [debug] ****
ok: [test_01] =>
msg: FreeBSD
PLAY RECAP ****
test_01: ok=4 changed=0 unreachable=0 failed=0 skipped=0 rescued=0 ignored=0