Appium 'Observer Mode'

I have use cases I would like to apply Appium to that would require Appium to interact with whatever is in focus on the device. This ‘observer mode’ is very different from the way Appium sessions currently work, so I am curious what factors lead to the decision that an Appium session would launch a single application and close it once it’s tasks are completed. Would it be possible to operate in an ‘observer mode’ using the driver technology Appium currently uses for automation?

Alternatively, if Appium could detect that the desired app is already running at the beginning of a session instead of relaunching it, that would solve a number of the problems I am trying to tackle. Please let me know if Appium can already do something like this.