We're now using kMIDIPropertyDisplayName, so this appears as "", e.g. "Widi Master Bluetooth" or "IAC Driver Bus 1" or "AMT8 Port 1" or what have you. If you create an external device in Audio MIDI Setup and make a connection to a device's port, the external device's name is shown instead. That should match other apps.
(This is as of the current main branch, which will be released as MIDI Monitor 1.5, sometime in the near future.)
Add a Bluetooth MIDI device and give it a name, e.g. "fadermaster". In the Sources section in MIDI Monitor, it appears as just "Bluetooth".
In other DAWs like Cubase or Logic it looks like "fadermaster Bluetooth".
(Investigate using kMIDIPropertyDisplayName instead of whatever we are doing now.)