Kirki is one of my favorite projects in the WordPress ecosystem. I don't only love the project but the developer who has put so much effort and care for this.

I also started a similar project for Customizer controls which is now not maintained: https://github.com/HardeepAsrani/o2/tree/development/ - it never had a stable release but some controls are used by hundreds of projects.

It's interesting to see how they evolve with Gutenberg. At ThemeIsle, we've started to use Gutenberg controls inside the WordPress Customizer. It's not the easiest setup for new developers but still takes a lot less effort than using making custom controls. Will be good to see someone abstract that process so the developer only has to define things in PHP and the abstraction takes care of the rest.