A Reddit post explained it best:

Yep go to window > new window then drag it onto your tablet. Next on your computer open your canvas. Then back on your tablet go window > new view and click on your document (should be the only choice) next on your tablet go to view and check the “show canvas only” option. You will have to do this every time you open krita back up as i do not know how to make this a default. Hope this helps and happy drawing.

I credit the post here:

https://www.reddit.com/r/krita/comments/lync65/can_i_mirror_kritas_drawing_area_from_one_monitor/

Bonus tip: save the layout as a new workspace so that you can automatically load it later! :D

I can’t wait to see the finished project! Still, I can’t help but wish that there was only one theming standard. :/

This is surreal. XD