How to Export Certificate on Windows in Python

I'm writing a Python program that needs to export a certificate from a certificate store on Windows. I've tried searching for a code snippet that does this but I'm having trouble finding one that does that. The important thing here is that I need to export the certificate with the private key from certificate stores that belonging to the machine and the current user.

My goal was to use a certificate to authenticate to Azure Key Vault. Based on the accepted answer, there's no way to retrieve a certificate from a cert store on windows. I decided to, instead, write a C# app to authenticate to Azure Key Vault and pass the secrets to the Python application.

You could send a subprocess call to powershell to export the certificates from the certificate store. This script prompts for a user password, then exports the certificates from the user's and localmachine certificate store that have a private key as .pfx files.

import subprocess
import getpass

pw = getpass.getpass()

proc = subprocess.Popen(
    [
        'powershell.exe',
        '-c',
        f'&{{ $pw = ConvertTo-SecureString -String "{pw}" -Force -AsPlainText;',
        'gci Cert:\\*\\My\\* |',
        '?{ $_.HasPrivateKey } |',
        '%{ Export-PfxCertificate -cert $_.PSPath',
        '-FilePath $env:USERPROFILE\\$($_.thumbprint).pfx -Password $pw}',
        '}'
    ],
    stdout = subprocess.PIPE,
    stderr = subprocess.PIPE,
    shell = True
)

out, err = proc.communicate()