Create a python virtual environment in a location your web server can access:

cd /home/user/html
mkdir -p /home/user/html/pyotp-env
sudo chown user:www-data /home/user/html/pyotp-env
sudo chmod 770 /home/user/html/pyotp-env

Create a virtual environment as apache2 user and activate it:

sudo -s -u www-data
python3 -m venv /home/user/html/pyotp-env
source /home/user/html/pyotp-env/bin/activate

Install pyotp:

pip3 install pyotp

Create the python script /home/user/html/pyotp-env/otp.py:

# Python script to generate authenticator OTP
import pyotp

# Your Base32 secret key (provided when setting up 2FA)
secret = "ABCDE1FGHIJK2LMN" 

# Initialize TOTP
totp = pyotp.TOTP(secret)

# Generate the current 6-digit code
current_code = totp.now()
print(current_code)

Check execution of pyotp:

python3 /home/user/html/pyotp-env/otp.py

Create a bash script:

vim /home/user/html/otp.sh
#!/bin/bash
source /home/user/html/pyotp-env/bin/activate
python3 /home/user/html/pyotp-env/otp.py
deactivate
exit 0

Give the script correct ownership and permissions:

sudo chown www-data:www-data otp.py

Create a php web page which calls the script:

vim /home/user/html/otptest.php
<?php
$output = shell_exec('/home/bco/html/otp.sh');
echo $output;