I understand your hesitance in promoting anything that can exacerbate the anxieties of people unnecessarily(our society is already bad enough at this), but as a parent, that anxiety was already there for me, and I think it's there for most other parents too. I used to wake up and check my daughter in the middle of the night because she hadn't cried in a while. This would have brought me peace of mind.
I highly doubt we would have trusted any device 100%. But it would have brought a little bit of peace of mind which new parents desperately need.
"probably ok" is exactly the level of confidence that left me with anxiety around this issue. It's not exactly a convincing statement to make for people worried about whether their child is still breathing or not. Regardless of the rationality of the concern.
This echoes my own experience in this area.
Might as well just attach a sensor directly to the kid instead. Something tiny, like wireless EMG electrode or MEMS accelerometer. Much less likely to get a false positive. (The problem is batteries, as usual.) Heck, a pulseoximeter.
It's a nice to think there are qualified people who can advise parents on this, but they don't exist. SIDS strikes even healthy infants. It's caused by a weakness in an osciallator network in the infant's cardiovascular system (modulo some percentage of infanticide). There's no known test for it but there is a simple solution: allow it to entrain to the mother's breathing by placing the infant near the mother.