Parts of it did become French in OTL (Savoy and Nice), but others became Italian (Lombardy, Piedmont, island of Sardinia).
My question is, with a PoD after the end of the Napoleonic Wars (1815), could the entirety of the Kingdom of Sardinia voluntarily develop a French national consciousness rather than an Italian one, and eventually merge into France?
If so, would Italy be united under the leadership of a different state (e.g. the Two Sicilies)?