Ajax is not working for logged out users

function add_ajax_actions() {
    add_action( 'wp_ajax_nopriv_get_blog_items', 'get_blog_items' );
}

add_action( 'admin_init', 'add_ajax_actions' );

admin_init only runs when the admin area is initialised. Logged out people can’t access wp-admin, so add_action( 'wp_ajax_nopriv_get_blog_items', 'get_blog_items' ); never runs. Move the add_action call out of that function and remove the add_ajax_actions function and it should work.

Have you considered using the REST API instead?