Exporting 3D models for dynamic texture changes on web We have received a few blender models which we want to make configurable by our users on the web. What is the best way to export the 3D model for this kind of operations? We were thinking the best way would be to export the textures for each part of the model separately and then apply them on the model as the user selects the materials, but we're not sure if that's possible.

The reasoning behind this is that the models have too many combinations which would be hard to export as a whole UV map for the model for each and every one. Also, the content is meant to be used on the web and a whole new UV map has approx. 5MB, whereas the part of the texture for e.g. sofa's legs is significantly smaller.

User would start with the default combination (default materials) and should be able to select the material on various separate parts of the model (example: wooden legs, red seat, etc.). After that, user can choose to open the configured model in AR View.

For all of this we're using the &lt;model-viewer&gt; web component by Google if that's any help. Thank you in advance.
The most popular format for web atm is GLTF, there is a Blender Addon for that.
Ofc. you cannot unwrap some vertices and ignore the rest, if you want separate UV Maps, you need separate objects (not files). Having an atlassed texture is always more perfomant than using multiple ones, not sure if that's an option in this case though. 
It's probably easiest to separate the parts into different objects, use different materials on each part and set their textures individually.  if your UV Layout alone is 5MB, consider decimating your objects either manually or by using the decimate modifier.