It's true, True. You can use dog hair to make yarn. Used to be a woman nearby who'd mix dog hair with wool to make various garments.
Now, to get into the coat issue. Not all dogs have a double coat. Generally the members of the working group do while sporting group dogs do not. Think of the grooming it takes to keep a spaniel's ears and coat smooth. They don't blow an undercoat once or twice a year.
Hard to believe the Pom (Toy group) was derived from the Spitz that pulled sleds like Huskies. Obviously they've been bred way down in size (ergo the high incidence of 'luxated patellas' in the breed), but thats another subject.
Cyndi alluded to the use of brushed - not shaved hair. Poms and other breeds with double coats require lots of brushing. The undercoat is soft and downy and the only part good for spinning.
I'd be very careful about shaving your dog for the hot weather in Ca. You indicated he doesn't need his coat, but he does.
The outer coat, 'guard hairs' stay when the undercoat is shed and that takes care of the animal's skin, protecting it from sunburn etc. Speak to a Pom breeder who will probably have a coronary, hearing that you shave yours. They are having quite a problem with dogs losing coats and not regrowing them.
Brushing and combing the loose undercoat is certainly more time consuming but will be better for the dog and you'll get much nicer yarn without all the coarse hair.