[?] group of "update" entities

Is there a way to create a group of the newly created update entities introduced in 2022.04?

I want to use the group binary result on/off to trigger a UI indication that at least one update is available.

You can use the legacy group format. https://www.home-assistant.io/integrations/group/#old-style-groups

I think a template sensor would probably be more appropriate here, unless you are going to use that group for something else as well.

State is the number of updates available. Attribute is a list of active update entity id’s.

  - sensor:
      - name: 'Updates Available'
        unique_id: updates_available
        icon: "{{ iif(states('sensor.updates_available')|int(-1) > 0,'mdi:cloud-upload','mdi:cloud-check') }}"
        state: >
          {% set entities = state_attr('sensor.updates_available','entity_id') %}
          {% if entities != none %} {{ entities|count }}
          {% else %} {{ entities }}
          {% endif %}
          entity_id: "{{ states.update|selectattr('state','eq','on')|map(attribute='entity_id')|list }}"