I’ve been searching through my collection of resources for brush tips you can use for this project. All of them are free to use and most importantly, free to have.
Most of the ABR-brush sets hosted on DeviantArt, for example, suffer from the fact that the creators have stolen them from everywhere and often do not even name or know their original creators, as they sometimes openly write.
That’s why in most ABR’s you’ll find the same brush tips over and over again, that is not only a problem of DeviantArt it is widespread.
The following selection doesn’t suffer on this issue!
This and other sets from Devin Elle Kurtz, TamberElla on DeviantArt, may be a start →
Devin Elle’s “Foliage & Grass Brushset” as a Krita-Bundle can be found here:
LJFHutch made some resources in GIMP-format, at least I find them great →
https://www.deviantart.com/ljfhutch/art/Foliage-Brushes-Directional-200905665
Like his grass? →
https://www.deviantart.com/ljfhutch/art/Gimp-Anim-Grass-Brushes-Set-163317084
All brush sets in his gallery:
https://www.deviantart.com/ljfhutch/gallery/25245650/brushes
Maybe Chickenbusiness’ brush tips created from photo templates would also be worth a look, you don’t necessarily have to apply them photorealistically? You’d get quite a lot of brush-tips to chose from.
Since most of the sets from Chickenbusiness were created with newer PS versions, they would have to be converted first, I can gladly give you the links to ready converted versions in my cloud should you be interested. Here is a link to a (not yet converted) set on DeviantArt, so you can get an idea of what to get →
https://www.deviantart.com/chickenbusiness/art/Never-ending-free-foliage-brushes-Dec-2021-899923645
Michelist
Edit/Add: Added the link to Devin Elle’s Krita-Bundle.