Agreed. It could have different types of coffee (expresso, double expresso, americano, etc) with automatic conversion to mg of caffeine and a text box to type into the exact amount of caffeine if needed

I feel like drinks tracking should be a separate system from food tracking where you can add the type of drink it is + the volume… I can see that this can also be useful for alcohol

Caffeine is a drug. I even use it to medicate ADHD. :) so just track it along with other medications.