This is an interesting concept, and I hope they do well.
There are several small independent companies making and selling sewing patterns. But a sewing pattern takes more than just templates to use when cutting fabric. There are sewing instructions, sewing diagrams or photos, lists of recommended fabrics, recommended notions, instructions on assembly order, instructions on seam allowances and whether seam allowances are included on the pattern pieces, needle and thread recommendations, stitch setting recommendations, and more.
Stitch Kitty is a (new? relatively new?) program from Wild Ginger software, which helps with all of that. It’s called a “professional guide sheet generator.” I have not heard this term before, not in sewing, and not in any other craft where patterns are sold.
I haven’t bought Stitch Kitty myself and I haven’t tried it. I’ve used sewing patterns in the past, but I’ve never tried to create one myself. I think their sample sheets look nice. I read through the software description. It sounds like Wind Ginger worked very hard to think of every variation a customer creating a sewing pattern might want, but I don’t have enough experience to judge.
I’m back where I started: this is a really interesting concept. I hope they do well.