from PySide6.QtCore import QObject, Property

class B(QObject):
    ...

class A(QObject):

    @Property(QObject, constant=True)
    def foo(self) -> B:        ...

reveal_type(A().foo) 

mypypoc.py:9: error: "Property" not callable  [operator]
mypypoc.py:10: error: Missing return statement  [empty-body]
mypypoc.py:14: note: Revealed type is "Any" 

from PySide6.QtCore import QObject, Slot
class B(QObject):    ...
class A(QObject):

    @Slot(int)    def foo(self) -> int:        ...

reveal_type(A().foo) 

mypypoc.py:10: error: Missing return statement  [empty-body]
mypypoc.py:14: note: Revealed type is "Any"