With @dROOOze's suggestion, I rewrote the code like this

from typing import TypedDict, Unpack, Required, NotRequired


class WidgetArgs(TypedDict):
    width:int|None
    height:int|None
    minWidth:int|None
    minHeight:int|None
    maxWidth:int|None
    maxHeight:int|None
    stretchFactor:int
    align:str|None
    color:str|None
    bgColor:str|None
    border:str|None
    fontSize:int|None
    fontWeight:str|None
    fontFamily:str|None
    padding:str|None
    hExpanding:bool
    vExpanding:bool
    name:str|None
    styleSheet:str

def popStyleArgs(kwargs:dict):
    retDict = {}
    for name in WidgetArgs.__required_keys__:
        val = kwargs.pop(name,None)
        if val:
            retDict[name] = val
    return retDict


class Label(QLabel):
    def __init__(self, *args, 
        labelImg:str|None=None,      
        **kwargs: Unpack[WidgetArgs]):
        
        styleArgs = popStyleArgs(kwargs)
        super().__init__(*args, **kwargs)
        ss(self, **styleArgs)

        if labelImg is not None:
            self.setPixmap(QtGui.QPixmap(labelImg))



class Button(QPushButton):
    def __init__(self, *args, 
        onClick:Callable|None=None,     
        **kwargs: Unpack[WidgetArgs]):
        
        styleArgs = popStyleArgs(kwargs)
        super().__init__(*args, **kwargs)
        ss(self, **styleArgs)

        self.clicked.connect(onClick)

It works well.

And in VSCode, I could get auto-complete suggestion like this, which is great.

When mouse hovers on the type, it will show definition like this, it's ok.

In Pycharm, even better, when hovering, it will show the referenced unpack types, like this

The only pitty is, I have to copy the document str of args to every widget's initial functions. The document still could not be shared. Any suggestions?