The two species you are interested in a incredibly different. Complete opposites Genus'.
As a general rule, most "Pygmy Chameleons" are 4" or less, However a few have been recorded larger. But since there are 20 or more identified species you'll have to narrow down which one you are speaking of. The most commun seems to be Rhampholeon brevicaudatus, often called "Bearded Pygmy Chameleon" and sometimes, more often lately they have been mislabled as "Kenyan Pygmy Chameleons".
The large majority of Pygmy chameleons are Wild Caught and imported. Although they arn't particularly difficult to breed, after you have an established group, but because of the low number of babies they produce and that it can be difficult to actually maintain their environment during some of North Americas intense seasons, you could be reproducing just enough to cover your mortality rate. Hardy? Hmmm, Hardly. These little boogers are pretty small and parasite treatment often leads to death itself. But if you do manage to buy more than a few, keep them in a roomy enclosure with the correct temperature, humidity, mold free, you could keep a few alive.
With the propper care, a Veild Chameleon CAN be a hardy chameleon. There are many ways to give good care and husbandry to them. The most important thing is, that you study the signs of problems, because when you have one, (Yes you most likely will) you need to identify it as soon as possible to provide treatment or to correct something.
I recomend you start with Veilds. Find yourself a Breeder that is trustworthy and recomended to you.
Although a bit outdated, Adcham has trustworthy information on many chameleon species. Utilise the Link below to your best, and pick up some books on the specific chameleon you are interested in.
Also below, a photo of one of mine.
Cute isn't he. Its hilarious when they "Play Dead"

Find your species here.
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CANADIAN CHAMELEONS