These will fail. 1) Not accurate enough; 2) Don’t account for walls/floors; 3) Will have low adoption where anything less than full adoption means fail; 4) can’t account for actually having a virus.

False positives and false negatives combined with lack of rapid result testing will also make this useless. This is why Google and Apple looked around the room and slowly tiptoed away.

Then we have the GDPR. Beat of luck making sure you’re compliant.

Just don’t. Humans do a better job with contact tracing. Not everything needs to be hit over the head with a technology cudgel.