I've completed this project yesterday;  (to anyone else reading this question) take inspiration if needed.
import random
stages = ['''
  +---+
  |   |
  O   |
 /|\  |
 / \  |
      |
=========
''', '''
  +---+
  |   |
  O   |
 /|\  |
 /    |
      |
=========
''', '''
  +---+
  |   |
  O   |
 /|\  |
      |
      |
=========
''', '''
  +---+
  |   |
  O   |
 /|   |
      |
      |
=========''', '''
  +---+
  |   |
  O   |
  |   |
      |
      |
=========
''', '''
  +---+
  |   |
  O   |
      |
      |
      |
=========
''', '''
  +---+
  |   |
      |
      |
      |
      |
=========
''']
#used to choose random word
random_lst=['addition','adequate','adjacent','adjusted','advanced','advisory','advocate','affected','aircraft','alliance','although','aluminum','analysis','announce','anything','anywhere','apparent','appendix','approach','approval','argument','artistic','assembly']
chosen_word = random.choice(random_lst)
#used to create display list + guess var
print("Welcome to hangman! ")
print("--------------------")
print("you have 6 lives." )
print("   ")
print (stages[-1])
display = []
for letters in chosen_word:
  display += "_"
print(display)
print("  ")
#used to check if guess is equal to letter, and replace pos in display if yes. 
lives = 6
game_over = False
#use the var guesses to store guesses and print at every guess to let player know what letters they tried already.
guesses = ""
while not game_over:
  guess = input("Guess a letter. ")
  print("  ")
  guesses += (guess + " , ")
  for pos in range(len(chosen_word)):
    letter = chosen_word[pos
    if letter == guess:]
      display[pos] = letter
      print("√")
      print("- - -")
      print("   ")
  if display.count("_") == 0:
    print("Game over. ")
    game_over = True
  elif guess not in chosen_word:
    lives -= 1
    print(f"Wrong letter. {lives} lives left. ") 
    print("- - - - - - - - - - - - - - - - - - -")
    print("   ")
  if lives == 0:
    print (stages[0])
  elif lives == 1:
    print (stages[1])
  elif lives == 2:
    print (stages[2])
  elif lives == 3:
    print(stages[3])
  elif lives == 4:
    print(stages[4])
  elif lives == 5:
    print(stages[5])
  elif lives == 6:
    print(stages[6])
  elif lives == 0:
    game_over = True
    print("Game over. ")
  print(f"letters chosen: {guesses}") 
  print("   ")
  print(display)
  print("   ")
  if lives == 0 or display.count("_") == 0:  
    break
  
if lives == 0:
  print("Game over. You lose.")
elif lives > 0:
  print("Congrats, you win! ")