You could always use native grasses and plants. There’s nothing inherently wrong with grass, but it’s important to have grasses that make sense within your ecological context. Using a bunch of non-native grasses may help for soil retention on your hill, but native grasses would do the same thing – arguably better since you can use ones with root systems that grow deeper into the soil and they’re more drought tolerant – and they’d be multipurpose (food, cover, nest materials, etc.) for native animal species. They’re often prettier and more colorful during the various seasons and take fewer resources to maintain once established.