Going by previous posts it would seem that anything added as an extra isn’t covered. Usually this covers things like better stereo, sat-nav, sun roof, leather interior etc. I would suspect that it would be classed as a front grill and the usual excess would apply, of course if it’s stupidly expenive Motability will probably notice and refuse to pay for it!.
Please excuse spelling/typos. Apart from being a clot it turns out I had one on my cerebellum that's now causing various problems!