I’m going to now admit that I don’t know enough to know how valid the testing is.
But, I can say that on an individual level it is easy enough to test whether a blood pressure regimen is effective.
Blood pressure is easy to test at home and the effect of a blood pressure regimen can be observed almost immediately - within 24-48 hours. So if the doctor recommends that I change drugs and measure my blood pressure daily under the same conditions, we can judge its efficacy.
In other words, I would be more comfortable with experimenting with different approved high blood pressure medicines than something like cancer medicines based on a startups recommendations.