This week (at the latest at the beginning of next week), there will be a several-hour technical break. A banner with detailed information about this will appear 24 hours before the planned work.
Ernest has previously said that this will be an upgrade to address several issues, such as those related to federation, spam and lack of moderation tools.
API stuff is listed in the 'merged pull requests' section (quite a few times), so unless I'm mis-interpreting what that means, I think the API should be going live as long as this downtime is for the updating of the instance!
This will help a LOT with people seeing /kbin as an option ... the mobile webpage is pretty fantastic, but I'm really looking forward to switching to the Artemis App as my daily driver.
I don't recall Ernest explicitly saying so, but the API is live on the artemis.camp instance, so hopefully it's in a state where it can be implemented as part of the core kbin code base. Perhaps the kbin codeberg can shed further light on this question.
API is part of the kbin code base (on latest develop branch). For example https://kbin.melroy.org also have API enabled. But kbin.social is still not upgraded until this day.