Careful about the Veneti, it was the same name of a Major Gallic Tribe in Gaul (France). It may do to do with out or just leave it as Boii for that region. You can make up your own units or use other mods for inspirations.
Boii no doubt had some good spearmen, though not as good as the Germanic people who arguably had the best. In fact, Germany most likely translates from Old German for "Land of the Spear". Boii probably had light cavalry and perhaps even chariots. They could also have had one handed axmen with shields and good light skirmisher small spear throwers ( a very widely common style of fighting among the celtic people and thrace and germany for that matter).
Etrurians very likely had chariots so even if the Boii did not at first, they may well have copied and improved on the Etrurians. Etruscans are often also said to have had archers, slingers, some small units of heavy horse and or bodyguards, axmen, hoplites. Axman may have just had armor with no shields and have been 2 handed even. A style likely copied from the old Minoans or Carians (who may well have in fact been Minoan settlers themselves).
If you plan to incorporate all subfactions that is a tall order. Technically btw, the etrurians were roughly divided into 3 major factions. Etruscans was known as Tyrrhēni to the latins (including Rome), and Tyrrhēnioi to the Greeks. These names are still reflected today in some place names.
A Etrurian (in their own language it was Rasenna Dodecapoli (etrurian league fo 12 city states), or the name Etrurians called themselves) League comprised most of the better known major cities such as Veia, Celvsin, Aritim (Arrētium in latin), Perusna, Velch and others.
Another League was the Campanian League. This was arguably Etrurians becoming independent of the north or a mix of other peoples certifying their new freedom as the north lost influence.
The third league was supposedly based in northern Italy, and may have been lead by either Arimna (Ariminum in latin) or Felsna. It may have been simply called the Northern League. It was north of the Dodecapoli.
You may also include perhaps Aequi, old enemies of Rome. Perhaps they were even rival latins. Though they may have not have been much if still around by this time. they were certain at one time a formidable Roman enemy.
There was also the Sabines, but like the Aequi may not have been around or enough numbers to add. This is if you are considering all peoples to potentially add though.
Brennus, the leader of a celt tribe called the Senones, sacked Rome a little over 100 years earlier. So they, if they were still around may have been another formidable people in Italy.
Croton may have Croton named version of what Tarantine has. Such as Tarentine Cavalry (that being the exception since it was a popular horse unit type all over the Greek world), and hoplies.
