The white grip clips are labeled:
Shelter Systems, pat no 4308647
The black ones (from both sources) add
(same pat no)
The hook part, that you are interested in, just has 'SD' molded on it.
The clip and hook are joined with a 1 1/2" loop of 1/2" ribbon.
The patent for the plug/collar part dates from about 1980. The idea for a pole clip probably wasn't patented (too obvious), though specific shapes can get a 'design patent'. I don't find anything of this sort for Sierra Designs.
Keep in mind that the pole hook is designed to fit a specific diameter of pole. Ideally the opening is a bit smaller than the diameter, so it has to flex when you attach it. The clips on my Kelty Zen tent are designed for the same size pole, but are quite as beefy.
What it comes down to, is that there isn't much of a consumer level demand for this product. People sew clothes, packs, and tarps, but few try to make a full blown tent.
Here's a different idea - sew the same 1/2 webbing to the tent, but use small center or side release buckle. You might be able find something small enough under the pet collar or bicycle helmet hardware sections. Some tents use buckles like this to secure unzipped tent doors. Door flaps are also secured with webbing ties, or ball and loop.