Free-hand drawing annotations

[Nidish96]

Are there any ideas for including free hand annotations?

Or at least, will it be easy to write an elisp function to include free-hand drawing on the pdf? I'm asking since I've been working on a small idea of using mouse clicks as inputs to tikz in latex to make graphics a little mode interactive (check out my repository here https://github.com/Nidish96/cart). It will be awesome if pdf-tools will allow me to programmatically draw the points a user clicks on as feedback.
How easy/possible do you think this will be ?

Thanks for a great package!
Nidish