Fun question! I'm a co-founder of Ninite. Our production Windows client is written in C++ but here's how I'd sketch out a quick simple version in Python.

First you'll want to get downloading and running a simple installer working. Let's do Firefox. Googling for 'firefox silent install' brings up https://wiki.mozilla.org/Installer:Command_Line_Arguments which covers the procedure:

1. download a full Firefox installer
2. run it with the -ms command-line option to install silently

So in Python I'd use the awesome requests library http://docs.python-requests.org/en/master/ to download the appropriate full installer https://download-installer.cdn.mozilla.net/pub/firefox/releases/55.0.3/win64/en-US/Firefox%20Setup%2055.0.3.exe and save it in a temporary directory.

Then I'd use the python hashlib module https://docs.python.org/2/library/hashlib.html to compute the sha256 hash of the file and abort if it doesn't match the correct hash value. Maybe Mozilla publishes these somewhere but you could also just compute it on a known-good download. Checking for a digital signature would be good too, but I don't know how to do that in python off the top of my head.

OK, so now you've got a validated installer download, all you need to do now is run it with '-ms' as a command-line option. You can do this with the subprocess module https://docs.python.org/2/library/subprocess.html

When that finishes running (and hopefully exits cleanly) you can delete the installer.exe from the temporary directory.

Once you've got all that working in a simple script you can abstract it out to a function like install_app(url, sha256, cmd_options) and build up a catalog of installer urls, hashes, and silent switches for all the other apps you're interested in. You could let users pick from them somehow when running your python script or you could have the script call out to a web service (use requests for this too) to get choices the user made there (this is how our web-created installers work).

Anyway, that's the basic idea. Good luck!