Why isn't Apple pencil able to bluetooth as a mouse with an iMac?

I am an online tutor/teacher with an imac that is "obsolete".

Creating keynote presentations without the ability to write causes the time to create to increase exponentially.

I can do it on my ipad, but my ipad is unable to airplay with my "obsolete" computer.

I am also unable to use the pen during live, online tutoring and teaching sessions.

The pen should be able to bluetooth to any computer just as if it were a mouse or a keyboard ... and it shouldn't block out and be incompatible with older computers.