As someone that has had high BP from their 20s, I would not trust any app to give me good advice, because I found that mainstream dietary advice, especially surrounding circulatory problems, is utter nonsense.
In my deep dive into the world of low carb, I learned that elevated levels of fructose/uric acid reduce the synthesis of nitric oxide, a known vasodilator, among other mechanisms (did you know that the explosive nitroglycerin is an effective vasodilator?). High blood pressure is reversible by reducing the amount of insulin spikes and ingested simple sugars, and low carb is the most effective method.
Yet most apps tend to pride themselves in "medically approved science here!", which means the usual story of eating less meat and saturated fat, and exercising more. "Leafy vegetables!"
The problem is that medically approved science that your GP offers tends to be about 25 years out of date, so we're at least a generation away before we have apps that tell you to stop eating bread, cereals for breakfast and heaping bowls of fruit, but instead eating real, non-sugary foods and not to shy away from saturated fat.
Now I am 50kg overweight than my first hypertensive diagnosis in my early 20s, and I have better blood pressure in about 2 weeks of eating fewer carbs than I did at the time when I was fit as a trout, but with tight arteries.
And don't get me started on cholesterol and statins, because I'll be here all day.
A link to get you started, if you want to base your app on up-to-date research: https://youtu.be/KlHPmJTihBc