Rendering Moodle shortcode in a theme's layout

columns2.mustache

{{!
This represents a theme's layout template.

To render the shortcode, simply call the renderer method defined in the renderer.
}}

<div>
  {{{ output.block_xp_progress_bar }}}
</div>

core_renderer.php

<?php
// Your theme's overridden core_renderer file.
//
// The one below is the renderer from Boost located in
// theme/boost/classes/output/core_renderer.php.
// You must adapt this in accordance to your theme.

namespace theme_boost\output;

defined('MOODLE_INTERNAL') || die;

/**
 * Overridden core_renderer.
 */
class core_renderer extends \core_renderer {

    /**
     * Render shortcode 'xpprogressbar'.
     */
    public function block_xp_progress_bar() {
        return format_text('[xpprogressbar]');
    }

}