Might be a bug… I want all micro data within the app (proteins, calories…) also exported to health

I just found this out: you share the foods (e.g. dinner) with another person and this person takes the foods into their app. In this case the data for proteins, calories etc. is not exported to health. You have to edit an entry and then data is exported.

You can verify this as following:
Let someone share 3-5 entries for dinner. Have no other entries for dinner on that day. Look into health data at the single data entries for that day -> there are no dinner entries. Then change one of the entries (e.g. 42grams instead of 40g) and save this. -> the entry will then appear as data entry in healt (time 20:00)