This is a really fun series of questions!

When we are talking about "turf," we are specifically talking about grasses that can be grown on a lawn and are mown. There aren't any native grasses that are suitable for this use. There are however many excellent groundcovers, sedges, low growing grasses that might be suitable for your situation. Lawn is a broader term that often included things like clover and other low-growing plants.

Non-native options

• Fescue grasses - often used in no mow mixes
  • These are taller than a traditional lawn and have a less neat appearance, but I think they look quite nice on hills.
• Clover - white clover is often used as a lawn alternative and attracts bees. It can be slick when wet.
• Liriope - resilient and easy to grow. 'No Mo' has a finer texter than other cultivars.

• Sedges - sedges are grass-like in appearance but aren't grass. They tend to look more similar to fescue grasses. Pennsylvania sedge is a native option. Not all sedges are native but there are many native choices.
• Prairie Dropseed - loved by birds but tends to grow tall in comparison to a traditional lawn. 
• Barren strawberry - not a strawberry but has gorgeous flowers.

These are just some ideas to get you started. I would suggest considering a mixture of plants with taller species towards the bottom of the hill and shorter ones towards the top so as not to block your view. I've also included a plant selector tool that will help you when making decisions as well as some articles. 

https://www.canr.msu.edu/nativeplants/plant_facts/plant-search-tool

https://www.canr.msu.edu/news/smart_gardeners_replace_worn_out_turf_with_thrifty_ground_covers

https://www.a2gov.org/departments/Parks-Recreation/NAP/Native-Plants/pages/nativegrassesrushessedges.aspx