Unfortunately not, the device name is shown but this is not what I'm after as it's not a unique identifier; if I have multiple devices of the same model they cannot be distinguished using this field alone, whereas they can using the 'serial_number' field which is present within each fit file.
When I look in the 'Device Info' box within the 'Details' tab all I see is 'Headunit Garmin Edge 130 (v3.8)' and not the device's actual serial number. When I look into the fit file itself using https://www.fitfileviewer.com/ I can see a 'serial_number' field within the 'file_ID' row, which is a ten-digit unique ID. That's what I want to be able to filter by within Golden Cheetah.
Is there any feasible way that I can extract this number and then use it to filter activities?
That is very surprising to me. As defined in the fit protocol (https://developer.garmin.com/fit/file-types/) the serial number is just another field contained within the file ID message, so why can't it just be read and store alongside other metadata such as the device name? This is especially surprising as you say that the serial numbers of any sensors paired to a device are read and stored within GC!?
I'm using version V3.6-RC1, the release notes for which specifically state "Import serial number and battery status for sensors from FIT files" as a feature, so this must be possible!
Out of interest, do you know why this is the case? Is there some logic to why the serial numbers of the sensors are kept and not of head units?