My spousal critter has developed a taste for these somewhat fancy hot dogs:
https://www.snakeriverfarms.com/american-kobe-hot-dogs.html
I prefer these somewhat more plebian meat-tubes:
https://hemplers.com/product/polish-sausage/
We almost never used to eat hog dogs, but have been hitting them fairly hard in the last six months or so. Last week I read somewhere a claim that such processed meat will knock you out of ketosis. True, false or “it’s complicated?”
As long as there are no hidden sugars, vegetable fats/oils, and you keep track of the carbs, I think you are fine. I see people posting pictures of Hot Dogs with their meals on here. I have bought Costco’s Sausages in a package after I read the label and I ate them cut up, with some vegetables I stir-fried in olive oil, and the rest of the family ate theirs in hot dog buns =).
The Waygu hotdogs look intriguing but for $12.00, I’d rather have a good steak.
The plebian sausages have a few ingredients you should try to avoid if you want your carbs as low as possible: dextrose, corn syrup.
Too many carbs will knock you out of ketosis whether the food is processed or not. Try to find sausages that don’t have added sugars or have as little as possible. Even if you have 5-6 carbs from a few sausages, it’s not going to revoke your keto license by itself.
I’ve seen these at Aldi. I’ll have to give them a try, either in some hot dog hash or an omelette.
I made a Keto chili cheese dog casserole with them but had 2 leftover so I put them in an omelette one morning. Delicious 
They shouldn’t have more than two (or is it one?) grams of carbs. I have eaten them on and off and have never been kicked out of ketosis. I think a straight cut of meat is healthier, though.
The SRF aren’t that expensive at our grocery store. A little under 8 bucks for a 5-pack, IIRC. Last week they were on buy-one-get-one-free special. I was VERY restrained and came home with only 6 packages, which I’m already beginning to regret!
We eat uncured bison hot dogs that Costco carries. No issues with them and they are very tasty. I love them with organic sauerkraut we get there too.
I’m not really worried about processed foods, as much as I am carbs. If check the label and they had more than a couple carbs, I’d pass. That said, I really don’t miss hot dogs anyway. Some sasages maybe, if my GF would make some keto sausage buns 