After a lot of work here’s what I’ve found with Blender. HiFi’s FBX reader is reading 4 types of material influence textures. Diffuse, Bump (Normal), Specular and Emission. Diffuse textures with transparency is still problematic in that Blender’s exporter does something incorrectly leading to any material with a transparent texture being 100% transparent. I found a hackish solution to fixing transparency by reprocessing the FBX via another program, but that then leads to Bump maps being lost - so its use has ended. If any programmers wish to work on this I’ll be happy to provide any of several hundred test cubes I’ve made to exhibit various failure or success modes.
Texture based specular (shine) control.
This depends upon what parameter of Specular effect your texture is controlling, usually it’s color, but it can also drive intensity and hardness of effect.
If controlling color - set material specular color to 0,0,0 - pure black. Leave intensity at .5 (default) and adjust hardness to whatever level looks right for your item. Higher levels for hardness leads to a more focused point of shine. Once you have that - in your texture stack be sure you enable the texture’s influence on specular - in Influences area you want the tick box by Color checked and others not. Might as well leave influence at 1 as it makes no difference in HiFi what you set it to. If your specular is too much your option is 1) modify the image making it darker/brighter or 2) change influences in Blender and bake a new map.
Make sure option Color is not checked under Diffuse section.
Normal (Bump) Maps.
Once added to texture stack you need to look at Image Sampling parameters being sure to check box labeled Normal Map and leave parameter under it set to Tangent. Then be sure in influences section - Diffuse color is not checked and under Geometry you have box for “Nor: 1.000” checked. As with specular, it seems changing the bump maps’s influence does not pass on - if it’s too strong/weak you have to fix by means similar to above.
Emission is same - its enabler is under Influence, Shading, “Emi: 1.000”.
If you don’t set influences then your material textures are not registered when FBX is parsed.
Changing specular color to pure black insures your texture is in control - at any other value you may not notice your texture isn’t actually controlling shine as the object will have shine from material’s base setting.
I realize this isn’t a step by step howto, but this isn’t easy mode stuff and I wanted to get some notes in place versus delaying while making up something more comprehensive.
Still to be determined… handling of multiple UV unwraps in same object. Lighting so I don’t have to shine flashlight at screen.