So lemme see if I understood right:

These companies did not want to participate in the driver solutions for users, so when Wacom did, it left them in the dust. They now whine that Wacom uses up all the "branding space" despite the term "wacom" having been first genericided into (like "kleenex" or "coke") then essentially blown away from the graphic tablets driver space, and even if they wanted to contribute they whine that the literally usable information they give to the user so the device is usable (like, coordinates and the like) is a corporate secret???

NGL, from here it sounds like they just don't want to do any of the work and want some FOSS peasant in Laos to do it all free for them instead.

It's the marketing department at Gaomon who contacted me. Here's the relevant excerpt:

I need to apologize, as I spoke with our technical team again today, and we have decided not to move forward with the Linux driver project at this time.

We carefully reviewed the project you shared with us (https://github.com/linuxwacom/wacom-hid-descriptors). While we appreciate the initiative, we found that this is primarily a Wacom-led project, and the potential impact for GAOMON would be quite limited. Even if we added support for our devices, the system would still show the device as a GAOMON model, but the overall setup would display Wacom branding.