So I'm considering this project done. The 1.4.3 version is on Github and can now be installed directly in the Godot editor via the Asset Library tab.
https://godotengine.org/asset-library/asset/1383
Also, just in case anyone finds this by search and is working on something similar, the vendor and product ids for all Space Mouse devices are listed on the 3Dconnexion FAQ:
Keyboard Pro: USB\VID_256F&PID_C664\…
Numpad Pro: USB\VID_256F&PID_C665\…
CadMouse Pro: USB\VID_256F&PID_C656\…
CadMouse Compact: USB\VID_256F&PID_C655\…
CadMouse Compact Wireless: USB\VID_256F&PID_C658\…
CadMouse Pro Wireless: USB\VID_256F&PID_C654\…
CadMouse Pro Wireless Left: USB\VID_256F&PID_C657\…
SpaceMouse Enterprise: USB\VID_256F&PID_C633\…
CadMouse: USB\VID_256F&PID_C650\…
CadMouse Wireless: USB\VID_256F&PID_C651\…
Universal Receiver: USB\VID_256F&PID_C652\…
SpaceMouse Compact: USB\VID_256F&PID_C635\…
SpaceMouse Pro Wireless Receiver: USB\VID_256F&PID_C632\…
SpaceMouse Pro Wireless (cabled): USB\VID_256F&PID_C631\…
SpaceMouse Wireless Receiver: USB\VID_256F&PID_C62F\…
SpaceMouse Wireless (cabled): USB\VID_256F&PID_C62E\…
SpaceMouse Pro: USB\VID_046D&PID_C62B\…
SpacePilot Pro: USB\VID_046D&PID_C629\…
SpaceExplorer: USB\VID_046D&PID_C627\…
SpaceNavigator: USB\VID_046D&PID_C626\…
SpaceNavigator for Notebooks: USB\VID_046D&PID_C628\…
SpaceTraveler: USB\VID_046D&PID_C623\…
SpacePilot: USB\VID_046D&PID_C625\…
SpaceBall 5000 USB: USB\VID_046D&PID_C621\…
SpaceMouse Plus USB: USB\VID_046D&PID_C603\…
SpaceMouse Plus XT USB: USB\VID_046D&PID_C603\…
SpaceMouse Classic USB: USB\VID_046D&PID_C606\…
CadMan: USB\VID_046D&PID_C605\…
https://3dconnexion.com/uk/support/faq/how-can-i-check-if-my-usb-3d-mouse-is-recognized-by-windows/
I already have the 7 most popular devices on my plug-in (the standard consumer models) but I may update my product id database in the future. I am just pretty busy and most of those are CadMouse and stuff I don't think Godot users are using. However, I will update at some point.