cmb2-field-type-list-generator.php

<?php
add_action( 'cmb2_after_init', function() {
	$metaboxes = \CMB2_Boxes::get_all();
	$unique_field_types = [];
	foreach ( $metaboxes as $cmb_id => $cmb ) {
			if ( ! $cmb->meta_box['fields'] ) {
			continue;
		}
		foreach( $cmb->meta_box['fields'] as $field ) {
			$unique_field_types[] = $field['type'];
		}
	}

	echo sc_array_to_li( array_unique( $unique_field_types ) );

	exit;
}, PHP_INT_MAX );

function sc_array_to_li( $data ) {
	$data = (array) $data;
	$str = '<ul>';
	foreach($data as $li){
		if ( is_array( $li ) ) {
			$li = $li[0];
		}
		$str .= '<li>' . esc_html($li) . '</li>';
	}
	$str .= '</ul>';

	return $str;
}