Roxanne, I apologize for not making it clear previously, but I don’t have a ketonix. I looked up how the ketonix and the breathalyzer each generate their displayed values and calculated the equivalences. I added my personal results with respect to diet as it “feels” right to me. I’ve also done blood glucose and infrequent blood ketone testing and used ketone pee strips when starting keto. Although there isn’t a tight correspondence between them, they have each given me a similar feel for what I can eat at any given time for my goal to be mostly in moderate ketosis.
My expectation is because a ketonix can generate a reading from 0-100 with a non linear scale that gives excellent coverage at the low end of the range it is a better tool for someone new to keto struggling to get into ketosis. If one is stuck in the blue zone feedback from 0 to 40 is going to give a better sense of where one stands and their progress than the 3 scores 0.00, 0.01 or 0.02. In the mid to higher ranges the difference in reported precision narrows. After one has been at keto a while the cheap breathalyzer is sufficient to guide one in achieving a targeted degree of ketosis.