Garibaldi was always a Republican, even if during the 1850s he realized that the unification of Italy would have been possible only through the Savoy. After landing in Sicily in 1860, he proclaimed himself "dictator" (the proclamation of Salemi on the eve of the victorious battle of Calatafimi), but only in the name of king Victor Emmanuel II. Later on, after taking Naples, he refused the entreaties of many of his followers who were trying to convince him to proclamate a republic in the south: the intervention of the Sardinian army became necessary not because his political loyalties were in doubt, but rather to avoid a march on Rome to end the temporal power of the pope (Cavour played very smartly in this narrative convincing Louis Napoleon that the only way to keep Garibaldi away from Rome was to acquiesce to a quick march of the Sardinian army to the south).
Garibaldi's ideal state was a republican one, but he was quite skeptic on the effectiveness of a parliamentarian democracy, at least before the masses had been educated and prepared to play a constructive role: his solution was always the same, a time-limited dictatorship patterned on ancient Rome. In his testament he wrote:
“… l’Italia deve proclamarsi Repubblica, ma non affidare la sua sorte a cinquecento dottori [i parlamentari], che dopo d’averla assordata con ciarle, la condurranno a rovina. Invece, scegliere il più onesto degli italiani e nominarlo dittatore temporaneo, con lo stesso potere che avevano i Fabi ed i Cincinnati. Il sistema dittatoriale durerà sinché la Nazione italiana sia più educata a libertà, e che la sua esistenza non si trovi più minacciata da potenti vicini. Allora la dittatura cederà il posto a regolare governo repubblicano”
"Italy must become a republic, but cannot put her fortunes in the hands of 500 doctors who will deafen her with words without sense and lead he to ruin. It is better to choose the most honest Italian, and appoint him as a temporary dictator, with the same powers that were granted to the Fabii and the Cincinnati. The dictatorship will have to continue until the Italian Nation has learnt to live in freedom, and her existence is no more threatened by powerful neighbors. Only then the dictatorship will be replaced by a traditional republican government." [translation is mine].
Garibaldi proved to be ready to renounce to his dictatorial powers when the emergency was over, but I would not bet on other prospective dictators (even if chosen among the most honest ones) to be so willing to do the same. It is also a (sad) truth that Garibaldi was scarcely interested in social reforms and during all his life was more at ease with the educated upper class than with the peons: maybe it is a good thing that Garibaldi was also not interested in parliamentarian politics