I disagree that they aren't useful. You could make similar arguments on any kind of home medical diagnostics, but any additional information seems better to me.

I disagree that they aren't useful. You could make similar arguments on any kind of home medical diagnostics, but any additional information seems better to me. 1. There is evidence that a still normal, but lower-than-expected SPO2 can be predictive of medical issues - https://journals.lww.com/md-journal/fulltext/2018/06220/can_a_pulse_oxygen_saturation_of_95__to_96__help.46.aspx https://journals.lww.com/md-journal/fulltext/2018/06220/can_... But mainly, 2. If there are overcrowded hospitals, having further insight into the severity of the situation seems useful.