Here's the list, with their product code, not including a bunch headed to Australia:
Let's talk about product codes. GPW is my publisher Gameplaywright, associated with Atlas Games (ATG). That's why you see GPW (if the distributor carries Gameplaywright) or a combination of GPW and ATG (GPW pickypacking on Atlas).
Some distributors listed don't normally carry Gameplaywright, which publishes niche but important products like The White Box Essays, Things We Think About Games, Hamlet's Hit Points, and The Bones. It's the meta of game publishing. There are a total of six Gameplaywright products out now, so that's why FLGS is number six. When you see an ATG code, it usually means they stretched to bring it in under the Atlas Games umbrella, which is pretty cool.
While I'm boring you talking product codes, let me point out that pesky space in the Alliance system. It's a space that has vexed me for years, as identical product codes between distributors wouldn't search if it had that space or if it lacked the space when searching with Alliance. Alliance recently changed their system to ignore spaces, which means you can now easily use other distributors codes when searching with Alliance.
That's especially important for Alliance as they've gobbled up distributor sales from competitors, especially with their exclusives, Asmodee being the critical one that kneecapped everyone else. Alliance went from a once every other week distributor with me to a once a week distributor, and part of that is difficult things to find with other distributors are now going through Alliance.
And finally, you'll see Atlas listed as AGG with PHD and ATG with other distributors. That's because the game trade has no universal standards for company product codes. WizKids might be WZK or WIZ or whatever the distributor felt like assigning that publisher on that day. There is no central authority to standardize codes. This is one of those horrible things that falls under "institutional knowledge," where only experienced people in my store know the various codes between distributors. We have several hundred of these codes we deal with on a daily basis and it's common for a junior employee to look up one code in one distributors system and erroneously put it in a point of sale field for another (a do over).
It gets worse too, the publisher can suggest codes for a product, which is welcome, but they or the distributor can also change codes. So you might be searching for a product WIZ1110 (or WZK1110) only to learn all the codes have been arbitrarily changed and it's now WIZ1111. If it's a marginal product, sometimes I just stop looking for it rather than trying to find it by name.