Exhaled CO2 measurement?

Capnometry sounds like an exciting new target for self-monitoring. Back in 2017 danwich reviewed the existing options for exhaled carbon dioxide monitoring and found that they ranged from $350 to “this thing is meant to be used in a hospital.” Is anyone aware of any new products in the last few years?

levlnow.com (not CO₂, but claims to measure your “fat metabolism” from your breath)