Category list of child pages

Hello! I have a list of pages:
{% set items = page.evaluate({'@page.children': '/items'}) %}

How can I get a list of categories for these pages?

My decision now:

{% set items = page.evaluate({'@page.children': '/items'}) %}
{% set catlist = [] %}

{% for item in items %}
    {% for cat in item.taxonomy.category %}
        {% if cat not in catlist %}
            {% set catlist = catlist|merge([cat]) %}
        {% endif %}
    {% endfor %}
{% endfor %}