Am i a fan of http://www.lumobodytech.com/ ?
Hmm, I need to think about this.
The proposition seems logical. A system that “knows” when you are holding  a static “correct posture”and holds you to it.
I think my only reservation is the idea that there is a correct  static posture. Certainly you need a stiff core, but your position when seated,  is best often  changed  ( see some of the observations by McGill).
But, if it  reduced your slouching by  say  15 minutes a day , and encouraged you to learn a bit more about your posture, and improved your general back hygiene,  the £80 seems totally worth it.
But, It could fall into the Standing desk error. There are very few safe static postures!  if you work at a desk, rotate between kneeling, sitting, sitting side on, standing ,holding a lunge.
I suspect , having tested a similar system ( the computer’s camera kept your head in a frame) that its  possible to get a “good reading” in as much as you haven’t “tipped” the sensor, but, you have  actually collapsed your back.
Ill try and test that out with this product.