Sidebars panel in customizer

It sounds like you are trying to create a custom WordPress panel that will display your footer widget areas. To achieve this, you will need to create a custom section in your WordPress Customizer that will be responsible for displaying the widgets. You can use the WP_Customize_Section class to create your custom section, and the WP_Customize_Control class to create a custom control for your widgets.

Here is a basic example of how you can create a custom section for your footer widgets:

class Footer_Widgets_Section extends WP_Customize_Section {
    public $type="footer_widgets";

    public function render_content() {
        // Your code to render the section content
    }
}

class Footer_Widgets_Control extends WP_Customize_Control {
    public $type="footer_widgets";

    public function render_content() {
        // Your code to render the control content
    }
}

// Register your custom section and control
add_action( 'customize_register', function ( $wp_customize ) {
    $wp_customize->add_section(
        new Footer_Widgets_Section(
            $wp_customize,
            'footer_widgets',
            array(
                'title' => __( 'Footer Widgets' ),
                'priority' => 30,
            )
        )
    );

    $wp_customize->add_setting(
        'footer_widgets',
        array(
            'default' => '',
        )
    );

    $wp_customize->add_control(
        new Footer_Widgets_Control(
            $wp_customize,
            'footer_widgets',
            array(
                'section' => 'footer_widgets',
                'label' => __( 'Footer Widgets' ),
            )
        )
    );
} );

This is just a basic example to get you started. You will need to add more code to the render_content methods of both the section and control to actually display the widget areas and allow the user to add widgets to them.