Two Factor Setup Workflow

Here are few screenshots of the two-factor setup (both OTP and U2F) by various providers:

Google

Sign-in Overview

OTP Overview

OTP Reset or Move

App Password Overview

App Password List

U2F Key Overview

U2F Add Key

U2F Add Key in Progress

GitHub

Two-Factor Overview

U2F Add Key

U2F Add Key - In Progress

Login - Username & Password

Login - U2F

Dropbox

Account Security Overview

U2F Add Key - Confirm Password (Step 1)

U2F Add Key - Information (Step 2)

U2F Add Key - Insert Key (Step 3)

U2F Add Key - In Progress (Step 4)

Login - Username & Password

Login - U2F