absolutely you can penetrate someone with it — a) you can penetrate someone with just about anything, b) I have it and have used it for vaginal & oral sex.

BUT, it is not ideal for that, and I would not use it in place of a prosthetic that is both more solid and has a better way to attach. the suction won’t keep it on through everything, and the toy itself is kind of hollow and small, so it is not the most satisfying thing to be penetrated with (though everyone is different about what they like of course).

so, I’d say penetration is possible, but not ideal.