The WebUI as is do not have 2FA as a module. For user management and authentication it relies on the underlying OS. The the user/ password combination you enter in the WebUI must match an existing user on the OS.
Turnkey linux (the underlying OS of MineOS) is a stripped down and streamlined version of Debian. So if something can bedone on Debian, you should be able to do it on Turnkey.
This guide tells you how to activate 2FA for SSH and SUDO: https://www.linux.com/learn/how-set-2-factor-authentication-login-and-sudo
Be warned though:
I am not sure how the WebUI, or more precisely the html authentication it uses to access the underlying OS’s user management framework, will react to suddenly having another hoop to jump through. Most likely you will get a timeout or an auth error since it’s not programmed to react to, and wait for, a secondary passkey prompt. This means I fear that activating 2FA on your system will lock you out of the WebUI, since the WebUI do not know how to handle it.
This version of MineOS is for the most part locked down for new features, since development for the next generation WebUI is underway. I’ll rebrand this thread as a feature request, so that it gets considered for this, or more likely the next, generation of MineOS