Double loop over dictionary and values

I want to configure systemd configuration files in a DRY way. I have this dictionary:

systemd_configurations:
  journald:
    SystemMaxUse: 100M
    Storage: persistent
  sleep:
    AllowSuspend: no
    AllowHybridSleep: no
    AllowHibernation: no
  resolved:
    DNS: 1.1.1.1
    FallbackDNS: 1.0.0.1
    Domains: "~."
    DNSOverTLS: opportunistic
  system:
    DumpCore: no

And I want to use a lineinfile task to apply the settings:

- name: Configure systemd
  lineinfile:
    path: /etc/systemd/{{ item.key }}.conf
    regexp: "^#{{ item.value.key }}="
    line: "{{ item.value.key + '=' + item.value.value }}"
  loop: "{{ systemd_configurations }}"

So the task would for every .conf file separately apply all the settings defined for that config file. e.g. for journald.conf, it would apply SystemMaxUse=100M and Storage=persistent

A working solution is to modify the variable a bit, according to this structure:

systemd_configurations:
  journald:
    - SystemMaxUse=100M
    - Storage=persistent
    - ForwardToSyslog=yes
  sleep:
    - AllowSuspend=no
    - AllowHybridSleep=no
    - AllowHibernation=no
  resolved:
    - DNS=1.1.1.1
    - FallbackDNS=1.0.0.1
    - Domains=~.
    - DNSOverTLS=opportunistic
  system:
    - DumpCore=no

And with the following task:

- name: Configure systemd
  lineinfile:
    path: /etc/systemd/{{ item.0.key }}.conf
    regexp: "{{ item.1.split('=')[0] }}="
    line: "{{ item.1 }}"
  loop: "{{ systemd_configurations | dict2items | subelements('value') }}"

But I'd like to understand how to achieve it with the original variable structure.