Reading from PX4 manual, it does state that rounds could be chambered manually.
I did a little test where chambered softly (moving slide by hand), extractor DOES catch the lip of the round although there is a slant on extractor to go over it "softly". Extractor can be moved outwards along with the help of the slant, but it's extremely firm and it catches the lip when done gently. It does not complete rounding the chamber and gun would not shoot.
If chambered hard letting the slide go, extractor applies greater force and with the guide of slant, leaps over the lip of round and round is chambered properly.
When chambered through magazine, it could be seen that round lip slips underneath the ejector.
From design perspective, it appears Beretta made sure that gun can be chambered manually with proper design parts (firm spring and slanted extractor face). However from practical perspective, one shouldn't do it too much as it does put unnecessary wear/tear/pressure on extractor.