simulate coding session in python

I would like to simulate a coding session (for video recording session : I am not a touch typist :-)

For example, I have a shell script like this (test.sh)

hello="Hello"
world="world"
echo $hello", "$world

And I have a python script like this (Simulate_KeyPresses.py) :

import sys
import time
import subprocess

def send_letter(letter):
  # V1 : simple print
  sys.stdout.write(letter)
  sys.stdout.flush()

  # V2: Test with expect (apt-get install expect)
  # cmd = """echo 'send "{}"' | expect""".format(c)
  # subprocess.run(cmd, shell=True)


def simulate_keypresses(content):
  lines = content.split("\n")
  for line in lines:
    for c in line:
      send_letter(c)
      time.sleep(0.03)
    send_letter("\n")
    time.sleep(0.5)


if __name__ == "__main__":
  filename = sys.argv[1]
  with open(filename, "r") as f:
    content = f.read()
  simulate_keypresses(content)

Which I can invoke like this :

python Simulate_KeyPresses.py test.sh

And it works beautifully. However when I pipe it to bash, like this:

python Simulate_KeyPresses.py test.sh | /bin/bash

I get

Hello, world

i.e I only get stdout and the key presses are not shown.

What I would like to see:

hello="Hello"
world="world"
echo $hello", "$world
Hello, world

I found a related answer (Simulate interactive python session), but it only handle python coding sessions.

I tried to use Expect, but it does not work as intended (does not show stdin also).

Help would be appreciated!