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.