[Python] How do I use the text of a tkinter button in a while loop?

I am trying to make a tic-tac-toe game using tkinter in order to learn the library. I have a 3x3 grid set up and filled with buttons and whenever you click a button it changes it to either x or o depending on the turn variable. In order to make the game stop when either x or o wins i am trying to use a while loop to determine it.

turn = "X"

btn = tk.Button(root, text = "", height = 4, width = 10)
btn.grid(row = 0, column = 0)

btn2 = tk.Button(root, text = "", height = 4, width = 10)
btn2.grid(row = 0, column = 1)

btn3 = tk.Button(root, text = "", height = 4, width = 10)
btn3.grid(row = 0, column = 2)

while btn.cget('text') != "X" and btn2.cget('text') != "X" and btn3.cget('text') != "X":
def on_click():
global turn
if turn == "X":
btn.config(text = "X")
turn = "O"
else:
btn.config(text = "O")
turn = "X"
def on_click2():
global turn
if turn == "X":
btn2.config(text = "X")
turn = "O"
else:
btn2.config(text = "O")
turn = "X"
def on_click3():
global turn
if turn == "X":
btn3.config(text = "X")
turn = "O"
else:
btn3.config(text = "O")
turn = "X"


This is the while loop I tried because I looked it up and some website said that .cget was the proper way, but it didn't end up working. I also didn't include the contents of the while loop as I don't believe they would interrupt it in any way. Additionally, as seen above when initiated my buttons contain no text and are only filled with either X or O when they are clicked. I am using IDLE Shell 3.13.0.

When I tried to run with this while loop it gave me this error code

Traceback (most recent call last):
File "C:\Users\jkoh2169\Python\Tic Tac Toe using tkinter.py", line 36, in <module>
while btn.cget('text') != "X" and btn2.cget('text') != "X" and btn3.cget('text') != "X":
File "C:\Program Files\Python313\Lib\tkinter\__init__.py", line 1828, in cget
return self.tk.call(self._w, 'cget', '-' + key)
_tkinter.TclError: invalid command name ".!button10"

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