Check if the user entered stop elsewise add the input to the list:

def listsample():
    sample = []
    killcode = str("stop")
    while 1:  # simply loop until stop is recevied!
        user_input = input("Enter number: ")
        if user_input == killcode:
            return sample
        sample.append(user_input)


def printsample(sample):
    print(sample)


printsample(listsample())

Out:

Enter number: 1
Enter number: 2
Enter number: foo
Enter number: 44444
Enter number: stop
['1', '2', 'foo', '44444']

Having to stop the code if a string is input by the user. you can create a custom IntList class (that inherits the list class) that only takes int values. Here’s how you can achieve this:

class IntList(list):
    # override the append method
    def append(self, value: str): # I have set the type of `value` as str as the input() function returns a string
        # check if the value is integer or not
        if value.isnumeric():
            super().append(value)
        else:
            raise TypeError("IntList can only have integer values")

Note: The above class stores the numbers as a string and not as integer.
if you want to store as integer you can replace the logic to:

class IntList(list):
    # Override the append method to ensure only integers are appended
    def append(self, value):
        if not isinstance(value, int):
            raise TypeError("Only integer values can be appended.")
        super().append(value)

This is terminal output for the same:

>>> sample = IntList()
>>> sample.append(10) # this goes okay
>>> sample.append("Hello") # this does not
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "<stdin>", line 4, in append
TypeError: IntList can only have integer values

Now to use this in your code:

# Custom class IntList
class IntList(list):
    # override the append method
    def append(self, value):
        # check if the value is integer or not
        if not isinstance(value, int):
            raise TypeError("IntList can only have integer values")
        # finally append the value if it is integer
        super().append(value)

# your code:
def list_sample():
    # create sample
    sample = IntList()
    # now since no string will be allowed to append,
    # kill code or kill command is unnecessary.
    while True:
        try:
            sample.append(input("Enter Number: "))
        except TypeError:
            pass # since we want to stop inputting.

Remember the input() function always returns a string, if you wanted to use the IntList implementation where the numbers are stored as an integer, You need to typecast the value of the input() function. At the same time, the code will throw an error if you try to typecast a string that contains letters to int.

Since no one else pointed out the mistake in your code which prevents you from getting desired output, I am listing them below along with the reasons and solution.

elements in a list are always strings

this statement is wrong, list.append methods adds whatever you provide it to append. The input() function is the one which returns everything as string.

Focusing on your first code:

def listsample():
    sample = []
    killcode = str("stop")
    sample.append(input("enter number"))
    while sample[-1] != killcode:
        if killcode not in sample:
                sample.append(input("enter number"))
        elif killcode in sample:
            return sample
        

def printsample(sample):
    print(sample)
    

listsample()
printsample(listsample())

Problem: When you enter “stop” your while loop terminates and therefore your sample list doesn’t get returned.

Solution: use else clause of along with while loop.

Problem: Strings are also appended, since you have not converted string which input() returns into integer.

Solution: typecaste result of input() to int.

After appling above fixes, your code looks like:

def listsample():
    sample = []
    killcode = "stop" # "stop" is already string, therefore no need to str("stop") 
    while killcode not in sample:
        value = input("enter number: ")
        if value.isdigit(): # check if all index of string are digits
            sample.append(int(value))
        elif value == killcode:
            sample.append(value)
        else: 
            print("Enter Integer or 'stop' only!")
    else:
        return sample[0:-1] # Return all elements execpt last that is 'stop'

def printsample(sample):
    print(sample)


printsample(listsample())

def listsample():
    sample = []
    while True:
        user_input = input("Enter a number or 'stop': ")
        if user_input == "stop":
            break
        sample.append(user_input)
    return sample

sample = listsample()
print(sample)