Isometric aiming with new input system using mouse position

I haven't seen a thread on here about this yet, so I figured while I try and figure this out on my own, I could create a post here just in case it's more difficult than I think it's going to be, as well as to inform anyone with the same idea.

So I'm making a isometric game, more-or-less top down actually.
How would you guys use the input from the mouse position w/ the new system in order to create Enter The Gungeon style aiming?

I'm sure there's multiple ways of going about it, lambda functions or otherwise, so if you can help me out, it would be appreciated.

 

I would also like to know how to this

 

Maybe you can find a answser here https://forum.unity.com/threads/solved-custom-mouse-position-origin.831724/ or directly here https://answers.unity.com/questions/932115/top-down-aim-at-mouse.html