Firefox has keyword bookmarks which is basically identical to bangs but you can customize them to your preference and they don’t require sending your query to a third-party remote service.
Just set the “Keyword” option in a bookmark and type mykeyword foo in the URL bar to search using your bookmark mykeyword. I use a lot of one-character keywords such as m for https://www.google.ca/maps?q=%s, g for https://www.google.com/search?q=%s, d for https://www.dndbeyond.com/search?q=%s and similar. I also have a keyword e which runs a bookmarklet that fills in a one-time email into the currently focused input field.