Is radio frequency sent over MQTT?

TA4SEZ asked:

Is it possible to add used frequency to nodes/stations? This would be good because in regions like Turkey, both 433 and 868 Mhz is used and would be nice to see for choosing devices.

Is the radio frequency (or perhaps radio region code?) sent via protobuf over MQTT in some capacity? Looking at MeshPacket it’s not jumping out at me, but there’s a ton of stuff in there so I might be missing how it’s referred to.