Attentive and interested dog owner <--> I pay a dog walker to exercise my dog
You don't need a device, you need to walk your own dog and bond with him/her.
This is like having kids, hiring a full time nanny and then saying you're a great parent because you have a camera on her to make sure she's nice to them whilst she's raising your children.
To your first point, if you don't trust your dog walker then you may also want to think and worry, and therefore question your decision of buying this, about the possibility of him/her taking the whistle off from your dog and attaching it to something else to give an impression that your dog was actively walking.
1. Detecting an abrupt change in sleep patterns in humans is useful.
2. Dogs are not humans.
Ergo: Detecting an abrupt change in sleep patters in dogs is useful.
Anthropomorphizing dogs is terrible. It is certainly one of the biggest causes for behavior problems in dogs.
Maybe it is because I have only ever had dogs that were bred for protection but I do not want to think about what my dogs sleep patterns are/were. Does whistle monitor for sounds so that I can disregard the change in sleeping pattern due to a siren? Foot traffic on the sidewalk? Thunder?
It's not anthropomorphizing to realize that mammals have a lot of physiology in common. If a dog scientist tells me that sleeping patterns are completely irrelevant for dogs because of some peculiar evolutionary adaptation, I'll believe it. But failing that, a decent null hypothesis is that it's probably pretty similar to humans (notice that my post started with "I'd imagine", not "It is a fact").
Also, just because X might be optimal for a pet doesn't mean that you have to do it. There's always something more you can do for your pet, but perfection is never possible.
And also, your incredible examples of confounding variables are not insurmountable, since sleeping patterns are successfully measured in humans even in suboptimal scenarios. Don't let the perfect be the enemy of the good!
Do you own a dog? If you do, have you watched your dog while it is asleep?
Just as humans, dogs go through sleep phases and even though humans have longer sleep phases; dogs have a REM phase. Once dogs get to the REM phase they're in a deep stage of sleep and the sound of an ambulance or foot traffic will not wake them up as easily as you think.
I've seen it hundreds of times throughout different breeds of dogs. I used to work part time for a vet when I was a teenager.
I have a GSD and a rottweiller. I am not saying that dogs don't have REM sleep. I'm saying that they sleep lighter than I do and they have for thousands of years. Cavemen let dogs eat eat their trash and in return the dogs acted as sentries.
Here's what I'll get:
1. I pay a dog walker to exercise my dog every-day for 1 hour. I want to make sure he is actively walking and not just sitting around the park.
2. Dog Sleep: I want to keep a healthy sleep vs activity percentage.
I think this is great. I love this trend of constantly tracking vs going to the vet every 6 months to find out whats wrong.