There is also at least one person who is producing these cross-bred dogs mainly just for their coat colors and calling them "American Corgis". There is no such breed, again, these are mixed pem crosses. It is basically a scam being disguised as "developing a new breed" and those who are producing these dogs do not have the best interests of the individual corgi breeds or other breeds they may be using, at heart.
Another important point to understand is that the merle color is dominantly inherited. This means at least one parent MUST be a merle to produce the color. This color does not occur naturally in pems because the foundation dogs used after the establishment of the Pembroke breed were not merles and the few who may have had the color during the earliest years were gone from the breed by the 1940s. This means that the only real way to get the merle color in Pems is to breed them to some other breed and all that makes is an expensive mutt.
The same applies to the brindle color which is also dominantly inherited and was rare in early Pembroke foundation lines. The color may have persisted in one line, but the last known case of a confirmed brindle in a purebred pem line occured in the 1970s in Canada. Current brindles have come from breeding to a Cardigan who was obtained deceptively and at barely a year old has been used for producing brindle pems without permission from it's breeder.
Because these merle (and brindle) pems are a mixed breed, they also cannot be legally registered with AKC or other qualified registries. If a breeder of these dogs tries to say they really are purebred and AKC registered because they have a Canine Partners, PAL or ILP number, they are being deceptive. This sort of number is only used so a dog can compete in AKC performance events and is no proof the dog is purebred or some sort of 'designer breed' approved by AKC in any way. At least one person who is creating mixes has been making this form of implied claim.
There are also less scrupulous registries, often founded by puppy mill or volume breeder groups or even the pem-cross breeders themselves, who will register these dogs and call them by a cutesy 'designer breed' name instead of what they really are, deliberately produced mutts, so don't be fooled when the breeder of these dogs say they come with papers.
Even if you never plan to show your dog and don't care about papers, please be aware that the main motivation of these people is making money. If they are unethical about registration, then what else are they hiding? The Cardigans they have used to produce these litters were oftren obtained deceptively, so buying one of these puppies is supporting their unethical behavior. Typically these breeders do not screen buyers, taking deposits from anyone and selling to whoever has the money to pay the price, even if the puppy is not a good match for their family. Many of these improperly placed dogs have already ended up in rescues. The adult dogs who were bred to make all these puppies also often end up dumped once they are too old or are used up from producing litter after litter and are no longer profitable.
"Home raised" claims may also only mean the mother is brought indoors to whelp, then after 3-4 weeks, the pups are weaned and taken from their mother. The mother is sent back out to the barn or some other outdoor kennel setup until she is ready to be bred again and the puppies also go to the barn, etc., until they are considered old enough to sell, sometimes as early as six weeks. Pups often may develop anxiety and other behavioral problems when they are not allowed to learn proper social etiquette from their mother and siblings during the critial weeks after weaning.
"Health tested" may only mean the dogs were examined by a vet who only gave them a basic health check, vaccines and worming, not that their owner conducted any actual health screening tests such as DNA checks for DM and PRA, hip, elbow and patella evaluations or eye checks, to name a few. Even those who may do testing typically don't know anything about the pedigrees or the relatives of the dogs they've obtained for breeding or the possible health, temperament and structural problems that might occur by crossing different breeds of dogs.
If you absolutely MUST have a merle, then please be prepared to wait, possibly up to a year or more in some cases. Ethical Cardigan breeders are not 'volume' breeders who pump out litter after litter, breeding their girls to exhaustion just to put money in their pocket and produce a flood of poorly bred and potentially unhealthy dogs that ruin the good reputation of their purebred parent breeds.
If you are impatient and decide to buy a merle pem mix anyways, be aware that you will be contributing to the problem. As previously stated, if one parent or grandparent was a merle or brindle Cardigan, it was likely obtained deceptively and used for breeding against the wishes of it's breeder(s).
And finally, two more things to consider.
First, the natural bob tail seen in many Pembrokes is very rare in Cardigans, so to get the 'bunny butt' look favored in pems, the breeder will have to remove the baby's tails by either docking (cutting off) or 'banding' (putting a rubber band tightly around the base of the tail to cut off circulation so it dies and falls off). The 'bunny butt' look might be cute in pems, but for Cardigans removing their lovely tails is not cute, it is just a travesty!
Second is that not all pups in a merle-pem litter will actually be merles and the others, sometimes even the entire litter, will usually just be ordinary tri-colors or reds. These ordinary color pups will not only be less desirable, but will also be nothing more than cross-bred 'mutts' and if they aren't sold quickly enough, may end up in a corgi rescue or dumped in a shelter or worse.
There are already far too many cute mutts (aka "Designer Dogs") waiting for homes in shelters and rescues, so why give money to support these corgi-mix/designer dog breeders who are just going to make more of them deliberately?