iPad Pros are amazing at video editing and audio production.

And I love it for doing architecture diagrams and also making changes to building plans for my home renovation. The 11inch model is also a great portable diary/productivity machine. I also have teachers in my family who use it for drawing and projecting mathematical formulas on a screen for their kids which they then email straight after the class.

They are selling well for a reason because people use them for different things.

I pretty much doubt that, unless you plug them into a nice 21" screen display and an hardware console to drive production.

Doable yes, amazing not really.

Most of what you mentioned there is drawing and using the pencil, which I concur works great.

I completely disagree about video editing and audio production. Sure it's doable for small family videos, but absolutely not for anything remotely pro.