Rather than having to search everything you can have your commonly used apps show in a list on the home screen. Personally I turn this off and have a clean home screen, but pin favorites above the search bar. Tapping the search bar shows the most commonly used apps.

Also I think gestures are not from search results but from the home screen. I use gestures on my blank home screen. I have it set up so a swipe down opens the notification tray, a swipe right opens the camera, swipe left opens search, swipe up opens browser. But this is customizable. Not sure if it works if you have the common apps list showing on the home screen.

I don't think KISS has smarts like Niagara seems to. Just showing commonly used apps is about as smart as it gets. To my knowledge no notifications on the home screen either, though you can add widgets so maybe that's solvable in some way.

Anyway, seems they are similar but Niagara is a bit superior with KISS being a bit inferior but FOSS, both good options!