Reply To: Fixed left vertical navigation layout – CSS and Customizer only

[Tom]

Give something like this a shot:

add_action( 'generate_before_left_sidebar_content','tu_insert_sidebar_logo');
function tu_insert_sidebar_logo()
{
    if ( function_exists( 'generate_construct_logo' ) ) generate_construct_logo();
}

Adding PHP: https://generatepress.com/knowledgebase/adding-php-functions/