You are right that you cannot enter the data yourself, as far as I know. But if your lab or physician uses a system that can let you download the records, they will be stored. So I have access to all my blood labs, but there is no easy way to graph them.
As far as I know, there is no App Store rule against making an app that lets you log the variables manually, nor is there a rule against making an app that graphs stuff. Keep in mind that there are a lot of Apple rules around HealthKit data to protect privacy, and writing such an app could be difficult.
You are right that you cannot enter the data yourself, as far as I know. But if your lab or physician uses a system that can let you download the records, they will be stored. So I have access to all my blood labs, but there is no easy way to graph them.
As far as I know, there is no App Store rule against making an app that lets you log the variables manually, nor is there a rule against making an app that graphs stuff. Keep in mind that there are a lot of Apple rules around HealthKit data to protect privacy, and writing such an app could be difficult.