Fieldgroups not showing on checkout

How can this be reproduced?

I think I can reproduce this behaviour:
- enable drupal/field_group module
- add field group elements (html element, details, etc)

- these elements are not being rendered in the checkout flow (see screenshot)

- these elements are being rendered within order edit for in Commerce (/admin/commerce/orders/1420638/edit) see screenshot

this issue might be related to how Commerce builds forms by using inline forms:
- see code in Drupal\commerce_order\Plugin\Commerce\InlineForm CustomerProfile.php "public function buildInlineForm(array $inline_form, FormStateInterface $form_state) ..."
- possibly related issue: https://www.drupal.org/project/commerce/issues/3068063 →

I also tried to install "Conditional fields" module and show/hide some fields on checkout based on user input (some sort of survey) - but because the form is rendered as inline form - conditional fields are not working (they do work on normal edit form page).

@anybody: any thoughts on how to resolve it?