The band it's operating in doesn't change whether or not it needs FCC certification. wifi operating on 2.4ghz is an unlicensed band, but it still needs certification for instance.

IIRC, Meshtastic has an is_licensed / “Ham Mode” setting that changes the software's regulatory assumptions and power limits so it can be used.

Many of the devices also exceed FCC specified power output on those frequences which is an even larger problem.