I had a problem…
when using a hand-painted Texture for the grassfield,, I couldn’t use the ‘From Instancer’ trick tomatch the blades’ color to the ground. Because that doesn’t work with UV Coordinates 😣
But….never let Blender bring you down…I knew there must be a way!
And I found it (probably a well-known trick, but I found it by myself and am proud of it 😉)
Here it is (very simple, just the way I like it):

You can paint without UV’s.
Now, this only works, because the ground is a 2 dimensional object; You can’t use this to paint Suzanne, for instance.
There might be a way to get this to work on 3 dimensional objects as well, but I don’t need that, so I can’t be bothered to try and find that way, especially, because my gut tells me it isn’t possible.