My only concern is that I have always had low blood pressure. The article highlights the lowering of BP and does not mention what the effect is on those with already lower than normal BP. (I wouldn’t want to pass out!)
My recollection, when I read the actual study some months ago is the absolute drop was rather small. I play with breathing, so was intrigued, but when I saw the small effect size, I wasn't motivated to try it.
There are other breathing techniques with known BP effects, that don't require equipment. I don't think they would lower anything to levels below normal.