Best way to manage y/n and password prompts through a Python script

Question

I am creating a Python script to install AUR packages but can't figure out how to detect yes/no and root password prompts.

So far what I have managed is to get rid of yes/no prompts using yes command, like this.

cmd = r'yes y | makepkg -si'
output = subprocess.Popen(cmd, stdout=subprocess.PIPE, shell=True, universal_newlines=True)

But still 2 problems persist:

1. Detect the password prompt: The password prompt appears mainly after makepkg enters in fakeroot. IDK how to detect that and supply the password from the script. There is no pattern actually. Some package evoke 1 y/n prompt while some prompt more than 1.

2. Enter actual password: Actually, I want to enter password through a GUI. So, basically, I want user to input password in a text box that I will create using Tkinter.

   tkinter.simpledialog.askstring("Password", "Enter password:", show='*')

I am confused how to implement this. I looked up this problem already and some Stack Overflow posts demonstrate the use of pexpect but I am having hard time understanding it. But if it can be done using the standard libraries then it would be great.