Need a help with picking a conductive and stretchable fabric/cord/yarn for breathing sensor

I want to make a breathing rate sensor with a chest belt. The idea is that when you breathe, the belt stretches and I want to measure that to count breaths. I was looking for kind of conductive and stretchable fabric/material that simply changes its resistance with stretching. I found suitable products on but rn they are sold out:

I also found a conductive fabric, but I’m not sure if they are stretchable enough:
Can you help me with finding the right product that is available on Danish site?