Thrilling forum

Prostituzione (1974) credited, as Gangster's henchman

Germanikus (2004) credited, as Thracian

Giulietta degli spiriti (1965) as Circus strong man

Sei iellato, amico hai incontrato Sacramento (1972) credited, in duel roles as Dimamite (clean shaven) and Murdock henchman (with moustache)

4 caporali e ½ e un colonnello tutto d'un pezzo (1973) credited, as Private Santi. Pietro has one of his most substantial 1970s roles in this little-known army comedy.

In the mondo documentary Italiani come noi (1963) as Italian bodybuilder

Pietro has two different roles in Caligola (1979), first as Muscleman on decapitation machine. This role isn't really visible in the commonly seen 156 minute cut, but is present in the re-edited Io Caligola cut released in 1984. It's also present as black and white workprint footage in the supplement material on various Blu-ray releases.
He also has a second role as Imperial bordello client, briefly visible among countless other copulators
The behind the scenes footage included on Blu-ray releases contain a brief glimpse of Pietro and is noticeably more revealing than what we see in the finished film

Non cantare spara (1968) (TV mini-series) - episodes 1 and 2, credited as "Il team di Musumeci Greco", as Saloon patron.

Episode 1
Episode 2
He also appears in Episode 4 in an additional role as Mexican bandit

Superuomini, superdonne, superbotte (1974) credited, as Villager.

Despite being credited in a film full of fight sequences, the only time where I could find Pietro appearing identifiably was in the background as a villager.

Diario di una vergine romana (1973) as Gladiator