Why would it need 5GHz? At most it needs to do two audio streams, which aren’t going to need lots of bandwidth

The upside of IANA doing it would be a standardised place for sites to move to. Without coordination, different sites would move to different TLDs, probably mostly based on what isn’t already registered. IANA could create a new TLD for this and give existing whatever.io owners a chance to register whatever.iox before its generally available