Simms waders "wet out" just like any other 3-layer, 5-layer garments do. "Wet out" doesn't mean that the garment leaks or gets wet on the inside, but rather that the face fabric absorbs some amount of water rather than shedding it all.
As a former fishing guide, I've gone through 10-ish pairs of Simms waders in the last 15 years. I've never worried about the DWR on my Simms waders as I tend to be pretty rough on mine and a fresh coating wouldn't last more than an outing or two. Additionally, I don't care if the face fabric gets wet and stays wet for a while in this context. The fabric that Simms uses on the outside of most of their waders doesn't seem to absorb much water either even after the DWR coating has been worn off.
Gore-tex makes something like a dozen different fabrics and several membranes used in a wide variety of applications. The easiest way to wade through (pardon the pun) the pond of information is to look at the hang tag. The products with the gold hang tags that bear the "guaranteed to keep you dry" is the one most of us are talking about. Their "waterproof, breathable" membrane.
Another important distinction to be aware of is the difference between the Gore-tex membrane, and other Gore-tex fabrics. The membrane is the "waterproof and breathable" plastic layer that gets laminated to other fabrics in the fabric manufacturing process. Gore makes a number of fabrics that include this membrane. 3-layer and 5-layer refer to the number of other fabrics or materials laminated to the Gore-tex membrane. A 3-layer garment will have a face fabric, the Gore-tex membrane, and a backing fabric that are all laminated together into a single sheet of fabric from which a garment is then built. Same with 5-layer which, for obvious reasons, is going to be much more durable and less leak prone over time, hence the reason for making waders with it. You don't see 5-layer used in things like rain pants and jackets because it is super heavy (by comparison) and quite stiff.
Lots of info here
https://www.gore-tex.com/support/frequently-asked-questions
There are many proprietary versions of waterproof breathable membranes out there that are often generally referred to as "Gore-tex" that are not made by WL Gore. Patagonia's H2No, Marmot NanoPro, Mountain Hardwear Vapor Dry and Dry Q etc.
The Kuiu Chugach line uses a 3-layer fabric and membrane called "Primeflex" made by Toray. I have no idea how it compares to products made by Gore, which have been the gold standard for years. Sitka uses Gore-tex.