No. This is not at all the question. A possible privacy breach is a serious issue, regardless of whether there is a working POC. If this data is somehow compromised, a stalker could get your identity just by following you a few minutes on the street.

I don't think it would require significant bandwidth; the data is just integers which can be collected, compressed and uploaded asynchronously (as part of another heavy upload such as someone sending a picture). The analysis part could be similar to how Shazam works, but that can be done on the server side so on-device performance isn't a concern.