You're right about the grass, it's too tall. I simply dumped some internal grass into it, but could better have taken some specialized veggies. This was merely to try getting the heather displacement and grass bumps believable.
It would be nice to have something low poly to carpet ground, like the grass object, but leafy. The problem always is that if you make a larger patch it won't follow ground too well. You need small patches, hence lots of instances. And repetititititiveness lurks.
I think you could do something with a plane/planet/sphere following the same contours as the ground, slightly elevated, and slightly displaced extra, with some procedural veggie-like dots and colors, added to a default shader, so you can have it semi solid, if you get my point, using the opacity tab.