The issue with this sort of broad-based testing is specificity. If these tests aren't highly specific then you're going to get all sorts of false positives clogging up the medical system. That can be such a large burden that proper care for sick people gets negatively affected.
In countries where medical care isn't the first step to financial ruin, people have regular checkups all the time. This sort of thing could just be used as a basis for further decision making (as are health apps right now), with only things that need immediate action turning into a "go to the doctor right now".
Which countries are those? There are a few screening and preventative care services which have proven valuable, and are covered in the US at no cost to the patient. But regular check-ups are pointless for most of us.
