Doesn't need an extension to search with a keyword (or a keyletter). In the settings for #Chromium or #Chrome open "Manage search engines", DuckDuckGo should already be in there, then change the keyword from "duckduckgo.com" to "!". Now you can search ddg by typing "! thing-to-search-for" (yes, you do need a space). For !Firefox and its derivates create a new bookmark with the location "https://duckduckgo.com/html?q=%s" and the keyword "!", and again you can search by typing "! stuff"
You want to break with old habits? Getting used to use a new search engine, online translator, etc. can be really hard. I just learned about #LeechBlock, a nice #Firefox and #Chromium extension which allows you to block certain URLs or forward them. You can set up rules like "forward google.com to startpage.com" or "forward translate.google.com to deepl.com". Now every time your bad habit kicks in, your browser will remind you what you really want to do. 😀 http://www.proginosko.com/leechblock/