Did you not read this a few paragraphs down the sane article?
For people who like to call BS, please follow through with the Kinsa data and report back. Commonly fever is listed as the first indicator of coronavirus.
"Kinsa's data is available for public and scientific analysis and the company plans to submit it to a medical journal soon."
“Fevers are often the first sign someone has coronavirus, which has spread quickly in large part because it can take days or even weeks for symptoms to appear.”
Fever is a symptom, so if it can take days or weeks for symptoms then that includes fever. Hardly likely to show almost immediate impact, though I admit that depends on how you define the terms. But even setting that aside, my response is “Duh! That's a few wasted minutes I won’t get back and memory cells that need to be purged in favor of something useful.”