Starting with Firefox 63.0, search shortcuts for Top Sites were added. Amazon and Google appear as Top Sites tiles on the Firefox Home (New Tab) page. When selected these tiles will change focus to the address bar to initiate a search.
Firefox lets you pin search for Google, Bing, Amazon, DuckDuckGo, eBay, Twitter and Wikipedia in your top sites.
This tutorial will show you how to add and remove search engine shortcut icons in Top Sites on the New Tab page in Firefox for your account in Windows 7, Windows 8, and Windows 10.