It is easy to deceive oneself that an app or a tracker equals health... better than pen and paper and minor instruction manual.
Now if you're actually working on safety critical health devices (say, insulin pump or oxygen meter or maybe a CPAP or perhaps heart monitor), then I hope you're working on cutting the price tag as they're super expensive for not really any good reason...
We were trying to figure out a reliable way to track sugar levels relatively nonincasively but found out that it was less accurate than a chart and simple alarm...
Sometimes being actually rational sucks, you see that your junk does not work or that you have to be smarter than super well funded geniuses at MIT or Stanford to matter. And have comparable fabrication and chemical analysis facilities and biolabs to even attempt anything.
Research is expensive. As in really expensive now in terms of hardware. As in some big universities not in USA being too poor to afford hardware. That's not even counting lab space to actually house it.