F-Droid is an alternative android app-store that is Open-Source and prides itself on providing other, Free and Open-Source Software.
Anyone can host an F-Droid repository and provide their own apps there, if they don't like the official https://F-Droid.org one.
Statistically speaking most people here are running on an unrooted Android device.
Thus, giving a slightly more advanced answer going over the Root Install method is mostly useless.
Either way, I've been doing this for 8 years, I know what I am talking about.