I am from USA and have resided in Massachusetts, Arizona and Washington state. All these states have pet shops that sell puppies. I don't think that there is a state in this country that does not allow pet shops to sell puppies unfortunately.
I don't know if you know about our crisis in the 'midwest states' with the "Puppy Mills" but these are places that keep adult dogs of many different breeds in generally very poor condition in small filthy cages. These private people will sell puppies wholesale to chain pet stores for about 35 to 100 US dollars and then the petshops mark up about 1000 percent. It is a shame but I have seen video on utube of other countries that do big business in the dog fur trade so it isn't that awful bad but a close second.
You can find almost any breed in a pet shop but the larger chains would be most likely to carry the toy sizes and the miniature size breeds because they willl stay cute and tiny for a much longer time so that the store has quite a while to keep the price above $1000 and still have a chance to get that price even if it takes a month to sell a dog for so much money. They would be likely to carry the furry little breeds too like the Poodle, Bichon, Yorkie, Maltese, Pom, Schnauzer, Chihuahua, Dachshund. Pug, Shih Tzu, Lhasa and most of the small 'designer' breeds. They will sometimes say they guarantee but there are usually big loopholes in the guarantee and truly the buyer won't be able to collect in the event something happens to the puppy.
Dog people always tell other people "Never Buy from a Pet store" but people go in 'just to look' and get sucked in and end up buying. Then they always say "I would never buy from a pet shop but I couldn't leave him there!" and so the cycle continues because the pet shop can always sell them eventually! I am one of those people who always goes in to look because I love all puppies but I have not bought a puppy from a pet store since I was a little kid. Many years ago, pet shops would sell to kids that had money but these days, they usually will not sell a puppy to anyone under 18. I think the reason is that legally, they will be forced to take the puppy back if the parents insist but if an adult buys a pup "ALL SALES ARE FINAL" is usually posted somewhere around the puppy area.