Utter, absolute and complete crap!
He masked his obedience to the House of Savoy and their porkies with "patriotic" and "progressive" words, but the only practical thing he did was leading an expedition -paid for and armed by the Savoy pederasts - to dismantle the Kingdom of the Two Sicily and annex it in order to:
1) pillage the treasure Naples had accumulated by taxing the shit out the peasants there while not spending shit just to pay back the huge debts the Savoy had;
2) allowing the same kind of parasites that ruled the south to just switch sides and keep going with their shit, just the King had to flee - that's the philosophy exposed in the book "Il Gattopardo" by the Count Tomasi di Lampedusa;
3) betraying all the shit he had been saying for decades by ceding control of it to the Savoy king immediately.
Marx was entirely correct when he called out his shit.
If you are interested in some serious, actually republican and socialist - or at least proto-socialist - people of that period, check Carlo Cattaneo and Carlo Pisacane.
GG made an enormous contribution, no doubt: he helped make this failed state exactly as it was supposed to be right from day one.
And fuck off to all the anarkiddies wetting themselves bc "some of his followers turned bakuninist"... which is highly debatable, btw.