A:AnswerThe CPAP machine won’t interfere with the sensors, in fact you can tell if you used you machine or not because the disruptive sleep due to snoring will be tracked and measured. The mat covers a decent amount of space so I don’t think you will have any issues and sleeping on your side or however does not affect the mat to measure your sleep.
A:AnswerI’d suppose so
Mine is under a memory foam mattress on top of wood slats and it picks up without error. I’ve also compared numbers to my Apple Watch and all seem with range of each other