Projectivy, Wolphin, and Button Mapper are all on Google Play with positive reviews. SmartTube isn't on Google Play, as it bypasses ads on Google's YouTube platform, so Google won't host it, but it is hosted on GitHub where it is well received, with plenty of stars.

Each has their own installation instructions, but the article consolidates them into a list of adb commands. If that's a method you like, it's nice to have everything in one place, but they can still be installed the normal way.

What "project"? It's just some adb commands that you can run on your TV/streaming box to disable built-in apps and change settings. The rest are just Android apps that are safe/legit.