Here’s a link to the Washington Native Plant Society blog listing a variety of sedges and rushes that can be used to replace lawn. They vary in height, sun, and water requirements but there should be some in there to fit your needs:

https://www.wnps.org/blog/choice-native-grasses-and-sedges-for-pacific-northwest-gardens?format=amp

If you still want grass, we have native grasses that you can sow from seed, and a lot of local garden shops that sell native seed mixes:

https://gardenshop.symbiop.com/collections/native-plant-seeds/products/low-grow-native-grass-economy-mix-sf?variant=43023485436145

and

https://ptlawnseed.com/collections/native-seeds

Would be my two places I’d recommend. And fall is the ideal time to be sowing.