I looked at a few places online and they all seem to pronounce it as "Bee-Vair" which could certainly come across as a fancy way to say "beaver" to some people...pretty funny, lmao!
Here's an excerpt from an article about the history of the Biewer. Check out the same of the names of these Biewer ancestors!
"On January 20th, 1984, the first blue, white and gold Yorkie, named Scheefloeckchen von Friedheck, was born to 1981 Dortmund Junior Champion, Darling von Friedheck and 1981 Dortmund World Champion Fru-Fru von Friedheck. This was the start of what is now known as the Biewer Terrier Breed."