Hey! I’m sharing today my perspective grids! 
(CC-0/Public Domain) and show how to use them in Krita: it’s a set of PNGs I drag’n’drop over the canvas.
I hope they’ll be useful for you! 
Video tutorial:
Download the ZIP with the grids:
https://www.peppercarrot.com/extras/resources/2021_Perspective-grids_CC0.zip
Thank you.
For the first few minutes I kept thinking “what a great idea. It would be even better if you could just set the vanishing points and have krita draw the grids”, and then comes the blog post for the feature suggestion! Then comes the observation that using pre-generated PNG layers and transforms doesn’t suffer the performance limitations of the existing assistants, which makes me wonder why. There’s something to be learned there I think.