The release dates are usually a good starting point
. Then it's a mix of the actual hardware (NTX boards have a specific API to "tag" a device and ID most of its components, c.f., the builtin ntx_hwconfig tool &
https://github.com/NiLuJe/FBInk/blob...nk_device_id.h for more details about that) and experience with KOReader porting and the various set of quirks/bugs/issues encountered on each board ;o).
As for a Nia image, the device appears to be incredibly unpopular (for... good reason, it has/had a very weird spot in the lineup), but @Szybet has one and works on custom hardware & software hackery on it, so he should have some backups. You can reach him on the Inkbox discord server, which is quite likely linked to in the Inkbox thread on this forum (EDIT: Or see the
tail end of the GH readme).