So I’ve made a Siri shortcut which lets you add all the nutritional data straight to HomeKit with water as well! It took a long time, but it’s totally worth it.
It adds all vitamins, which are available in the HomeKit. You just choose how many scoops you’ve added along with how much water. It gets you more data than you would using myfitnesspal.
*you need ‘shortcuts’ from the App Store.