I have added new checkbox called "Split by Country" as a filter in Orders Report section.
$fieldset->addField( 'split_by_country', 'checkbox', [ 'label' => __('Split by Country'), 'name' => 'split_by_country', 'data-form-part' => $this->getData('target_form'), 'onchange' => 'this.value = this.checked;' ] );
Then I added a new column in grid called "Country".
$this->addColumn( 'country', [ 'header' => __('Country'), 'type' => 'string', 'index' => 'country', 'sortable' => false ] );
What I want to achieve here is, when a "Split by Country" checkbox is checked then in a grid I want to display entries order by country.
Please suggest me a solution for this.