The armored "charioteer" wearing a beretta is obviously the ruler, however informally the Medici were defined in that role, necessarily is Lorenzo in the context of this evidence, and indeed the palle are on the wagon's cloth covering.
I would further argue that the odd inclusion of dark grey (perhaps used to indicate velvet, vs. the black of the armor) on one of the chariot pennants (it deviates from the theological red/white/green usually employed by the Medici) as well as the black shield held by the Page of Swords are a sign of mourning for Lorenzo's deceased brother, Giuliano (killed in the Pazzi/Sixtus coup attempt in 1478, and calling for Lorenzo to be depicted in armor, if not as an avenger, then at least as protector of the city against subsequent attacks).
Why a halberd? Florence society was obsessed with aping the French, especially Burgundian, courts at this time, with Lorenzo's dad, Piero, even making loans to the Duke of Burgundy (R. Trexler, Public Life in Renaissance Florence, 1980: 442). The year before the Pazzi conspiracy, this happened to the Duke of Burgundy:
So the charioteer was brandishing a weapon associated with the death of ruler known for his martial prowess. The message was none too subtle....at the Battle of Nancy (5 January 1477). He himself perished in the fight, his naked and disfigured body being discovered some days afterward frozen into the nearby river. Charles' head had been cleft in two by a halberd, lances were lodged in his stomach and loins, and his face had been so badly mutilated by wild animals that only his physician was able to identify him by his long fingernails and the old battle scars on his body. https://en.wikipedia.org/wiki/Charles_the_Bold