@GuineaFowling
Murray McMurray Hatchery has a newly developed breed called the Whiting True Blue named after geneticist Dr. Tom Whiting which McMurray Hatchery claims are true blue egg layers and the breed comes in different colors sort of like Easter Eggers where there are different patterns and colors of feathers and different leg colors. McMurray seems adamant that they are true blue eggs.
Then there's the Arkansas Blue which were developed by UofA and apparently a cross between an Araucana and Leghorn. Only about a half dozen breeding flocks in the USA last I researched.
Then of course as you know there are the Cream Legbars but like Easter Eggers it seems they lay more greenish-blue rather than true blue eggs much to the frustration of breeders.
And any time new breeds are created it takes generations of birds to be perfected and standards established and presented at poultry shows before the breed becomes an "official" accepted breed and no longer just an experimental mutt mix.
Seems that Araucanas were the original blue egg layers that were inter-bred with productivity type breeds like Leghorns, etc, to increase egg size and egg productivity because Araucanas were not the best layers.
EE's & Ameraucanas were developed starting with the original South American Araucanas or Quechua or whatever history you read about the original blue egg layer breeds. I tried researching the history of blue egg layers and facts were conflicting. I decided there really is no original TRUE breed of chicken. In the long run a TRUE breed is one that after it has been created will breed generation after generation holding the same characteristics as its parentage. I'm over-simplifying but its my own conclusion after years of asking questions, researching history, and talking with breeders.
We ended up deciding we're more interested in the personality of chickens as our choice of pets and that the color or size of eggs was not our primary goal. Yes, we wanted eggs but the colors became inconsequential. When we dealt with so many temperament conflicts trying to get a colorful egg basket it turned out in the end that it was more important to us to have compatibility in our choice of breeds.
We all have different poultry goals/interests and it's both fun as well as frustrating to finally decide what our final choice will be.