I’m going to northen italy in the summer with some mates. There seems to be a growing range of places in the north. we’ve not booked a guide yet, but I’d google “Molini freeride” and “rivierabike” for guiding on the coast, south of Turin. I’d also google “alpi bike park” for some more alpine stuff. The lakes (esp. Garda) have loads of riding, some a bit more xc, some pretty full-on.
Further south there’s less organised stuff and I don’t know about The legalities of Italian trail access. I lived near Bologna for a while in the early ’00s, but only rode roadbikes. That was fantastic, despite the constant battle of trying not to be dropped by the locals!