I am a person with Type 1 Diabetes (T1D). Knowing certain up-to-date data about my body is essential for a tight schedule of multiple daily precise treatments. Hence my opinion on the question is, of course, biased. I consider myself a T1D Cyborg, as parts of my body functions have been replaced through technology. I wear a blood glucose sensor and an insulin pump 24/7. I let an algorithm on my phone decide whether to administer a hormone that could be lethal if incorrectly dosed. I benefit from both sensors (in this case, the CGM) and actors (the insulin pump) connected to my body, and being readable and writable through APIs. Regarding my chronic disease, my available human APIs are a blessing to me.

Recently, one of the CGM (continuous glucose monitor) manufacturer announced the availability of their sensors for sport. You could predict through monitoring blood glucose exactly when your body needs sugar to keep up performance and not fall into a dip triggered by low glucose levels. Another company dedicates its whole existence towards this hardware's API.

Your smartwatch knows your exact body functions, knows when you exercise, fall, sit too long (for whatever reason 💩) or are experiencing stress. All of this data is available through the respective apps or a central app on your platform, e.g. HealthKit on iOS.

It's definitely not a technical limitation to make the leap from sensors to actors. I did when I started using my insulin pump. People with a pace maker have an actor, that may be just as lethal as it is healthy. But these actors don't always need to be invasive to the body. You could think about skin patches for other hormones that reduce stress through dispensing a hormone, or maybe even only set free a certain fragrance that helps relief.

I understand people are ok with sensors, and shy away from actors in or on their body due to the invasiveness and potential security issues. There's a strong benefit for people with a (chronic) disease, and these patients are more willing to let technology invade their bodies if it helps ease the burden of their disease. For those people, security is often not an issue. But building trust would definitely help a general audience get more comfortable with the thought of using actors that could kill them.
(You could kill me if you knew the serial number of my insulin pump and did some reading. I don't spend too much time thinking about it. Just yet.)

How far away are we really away from human APIs in everyday life. And will it be a blessing? Or it it just another area of life that homo sapiens sapiens is trying to subdue? Please share your thoughts in the comments.