What about some scotch moss or irish moss??

In my experience Sagina subulata (Irish and Scotch moss) needs full sun. Though it looks like moss it isn't and it grows poorly and weedy in partial shade.

For shade there is Ajuga or Corsican mint and I'm sure others.

I've linked the Stepables website. They have a search that you can use to narrow down your search.

Here is a link that might be useful: Stepables

I think it depends on what look you want. I have literally hundreds of feet of paths and walkways. I have stepping stones, 3x3 spaced pads, and flagstone. I used blue star creeper for the stepping stones and some of the spaced pads. Then I transitioned to washed 5/8" minus when the pads entered the back yard (the steps are rose/charcoal with gray curb on both sides). I am tickled with both. In my pond area, I wanted a more natural look so I chose random Montana Bronze flagstone and Platt's Black so it would not be such a contrast and get too busy. I was going more for a living mortar look and as it fills in, it really looks great. Either of these could go sun/shade me thinks :-)

Here is a link that might be useful: {{gwi:1089251}}

Here's an old picture of the steppers and bluestar creeper. It's a totally different look than the Platt's.

Here is a link that might be useful: {{gwi:23152}}

I probably wouldn't try Cotula or corsican mint where you are because of the possibility they might not adapt well to your climate. You might look at thyme or blue star creeper, which ought to be able to take quite a bit of shade where you are.

I planted blue star creeper between big slabs of broken concrete and it turned around and grew the other way into my shrubs and perennials and left between the slabs bare. I love it but it is soooo annoying.

Just a word of caution re blue star creeper. See my post, "What's the best way to kill blue star creeper", on Sep. 6. Your photo suggests that bsc would work much better than the scenario we had; i.e., as a lawn replacement. It is beautiful and steppable, but so very invasive.

Also, when we started the project, we needed a lot of starter plants (at least, we thought we did, not realizing how fast they spread). So we ordered flats through a local nursery and cut them up to plant, rather than buying a gazillion of those small containers, thereby saving a lot of money. The nursery got the flats from somewhere in Oregon, but they weren't available year round and might not be available now. When we were shopping, we just happened to see some ground covers in the large flats; never realized before that they came that way. They were out of bsc flats at the time, but special ordered for us. You might ask at your local nursery once you decide. Good luck on your selection!