You can go to each AP and select "connection log" to filter by 2.4GHz or 5GHz to see the clients on each AP. That's not necessarily a report as you inquired about but does show clients on the 2.4GHz SSID.
Or you can go to each AP and select "health" and filter by band as well to see clients on the 2.4GHz SSID.
The "timeline" option might provide you the best option to see all 2.4GHz devices as it allows ALL APs.
