He's the only one in that lineup confirmed to not resemble his toy. The rest all resembled the toys seen thus far.
I would challenge this. Thus far, all of the 13 toys have resembled the AotP statue art in terms of broad strokes. That includes Star Convoy. Certainly, his artwork torso looks a lot more like PMOP than Star Convoy, but otherwise that's straight-up classic Star Convoy. The art is basically the toy we got with a PMOP torso plate tossed on top, presumably just to mess with us.
That level of difference from artwork to toy is not at all unique to Star Convoy. Micronus's toy torso features parts of the Armada Minicon symbol, which resembles his artwork torso only to about the same extent that both PMOP and Star Convoy both have Optimus Prime torsos: they both have slanted lines. They're angled the opposite direction though, and don't make the same sort of design as in the artwork. Alpha Trion's artwork resembles his G1 cartoon appearance, and so does his toy. Aside from that common root, they're clearly two independent designs with none of the details matching up. Likewise, Quintus and Amalgamous clearly used the same Covenant artwork as a starting point, but diverged pretty significantly. I'd argue that Amalgamous especially has much greater deviations between his toy and artwork than Star Convoy.
It seems to me that the line artwork was done at some point where the initial wave of toys was pretty much finalized, the rest of year 1 was pretty far along, and year 2 was all early concept work. There are only three of them left to be revealed. Barring a huge surprise, we already know what Vector will look like via his early release in Legacy. We already know Liege Maximo will be derived from his G2 appearance like the art, but I'd expect the details to vary like the others. That just leaves Nexus as the last real question mark.
Coming at the end of the line, he was probably still very early concept at the time the art was created. That leaves the greatest opportunity for things to have changed between then and the final design. I certainly wouldn't be shocked if he ultimately does resemble the artwork to some degree. However, I wouldn't expect him to be all that close to it either.
If I had to guess, I'd say he'll probably have a similar sort of brutish build, and probably some wings on his back. But even then, I wouldn't be surprised if that leaked combiner listing is what ultimately resembles the art, with the Voyager toy only being a torso component that looks completely different. Aside from Optimus being Leader-sized in the art so as to not tower over everyone else and Micronus being scaled up to the size of his armor, the rest all are scaled pretty similarly to their toys. That makes it pretty striking that a guy getting released as a Voyager is so much bigger than the Leader Onyx right next to him.