App access to track my food intake and my reaction
You can chose, I have created an webapp which also works on a cell phone, you can use it as it is, but your data are in that app backend. Secured and your privacy is secured. But if you like to create your own little APP then I can show you what I did with Appsheet.
This requires maybe 2 hours of your and my time, you would use your google account to build your own app on your computer with my remote instructions. That ensures the data are in your ownership, you decide what to do with it.