Remove sanitize from render_template

Sure,

You can take the extension example code, even without fields. Just add a <form></form> in the template file.

add_filter( 'rwmb_meta_boxes', function( $meta_boxes ) {
    $meta_boxes[] = [
        'title'           => 'Hero Content',
        'id'              => 'hero-content',
        'description'     => 'A custom hero content block',
        'type'            => 'block',
        'icon'            => 'awards',
        'category'        => 'layout',
        'context'         => 'side',
        'render_template' => get_template_directory() . '/blocks/hero/template.php',
    ];
    return $meta_boxes;
} );

template.php

echo '<div><form><button>Label</button></form></div>';

Using render_callback doesn't make a difference.