Absolutely love Niagara. The most used shortcut is the Niagara button. A swipe up to get a new Firefox tab and I can do searches without having to interact with Google's apps
It's the floating action button in the bottom right. You can enable it in settings, and have a tap on it or swipe on it bound to two different apps or shortcuts. A shortcut I use it for is to open a new web browser tab to do searches.