Adding 2 frequency ranges is more expensive. If you're going to choose just one, you should choose the one with the greatest backward compatibility.
replyRealistically 2.4Ghz is far from "greatest backward compatibility" since there is a real benefit of running 5Ghz and 6Ghz only networks.
reply2.4Ghz makes sense because this tiny device does not need high speeds Wi-Fi connection, and deployment scenarios benefit from 2.4 GHz penetration more.