We feel like a broken record (for those of you who remember records) because we get so many questions wanting a low-maintenance, low water native turf grass for shade. Thunderturf is a Native American Seeds branded grass mix; you are correct, it requires full sun, which we consider 6 hours or more of sun a day. A team led by the Lady Bird Johnson Wildflower Center has developed a grass called Habiturf, which has all the specifications you are asking for EXCEPT it needs about 5 hours a day of full sun. Read the entire linked article; the last question under "Frequently Asked Questions" on that site deals with overseeding an existing lawn.
When we are asked for native grasses for turf in a shady situation, we feel our best alternative is to offer them some other kind of groundcover. From a previous Mr. Smarty Plants question:
"So, here's our suggested plan. An area that is not going to get regular watering, or lots of sun, or consistent weeding and maintenance is not a very good candidate for turf. We would suggest, first, you select the areas where foot traffic will occur, and/or you don't think much of anything will grow. Consider getting decomposed granite to use not only for pathways but for beds in which some plants, like succulents, can grow. From the website The Human Footprint, here is a very comprehensive article on the use of decomposed granite. Another article from Landscape Design Advice Decomposed Granite as Paving Material adds more information.
Too much hauling and expense? Next possibility is mulch. First, read our How-To Article Under Cover With Mulch. This article details the various materials that are used as mulch, including decomposed granite. If you want to use that for pathways or gardens, you might consider an edging of native stone to keep the mulch from creeping, which the shredded hardwood bark mulchs will tend to do. Some areas may need renewal every six months or so, but as the mulch decomposes it will go into the soil to improve drainage and the texture of the soil."
If you have a few sunny spots close to the sidewalk, that sounds like a great place for a flowering border of bright-flowered plants that like the sun. Mulch the bed, as suggested above, after you have put those plants in the ground at the appropriate time of the year. We are going to list both shade tolerant flowers and shrubs, maybe even some succulents, as well as some that would do well in that sun around your sidewalk and dress up your entrance. We will check to make sure all our suggestions are native to the area of Travis County. Follow each plant link to our page on that plant to find out what its growing conditions are, projected size, water needs, etc.
Succulents for part shade (2 to 6 hours of sun daily):
Flowering Plants for Sun (6 hours or more of sun) or part shade:
Groundcovers for Shade: