What are some alternatives?
When comparing CopperheadOS and MIUI, you can also consider the following products
LineageOS - Operating system for smartphones and tablet computers, based on the Android
Replicant - Replicant is a distribution of Android that is 100% Free Software.
Android - Android is an open source mobile operating system initially released by Google in 2008 and has since become of the most widely used operating systems on any platform.
Resurrection Remix OS - Resurrection Remix ROM is ultimately full featured, stable and combined with the best features of...
Ubuntu Touch - Read more about Ubuntu Touch. Our free and open source mobile OS is made and maintained by UBports! We care about your freedom and privacy.
AOKP - AOKP stands for Android Open Kang Project. It is a custom ROM distribution for many Android devices.