I use this a lot, but the problem with this, that still hasn't been fixed after all these years, is if you have 2 or more keyboard layouts, you can't make more than one bookmark pointing to the same URL with different search prefixes.

So if, for example, you wanted to make

> x <search_term>

and

> y <search_term>

both work the same, x and y being letters from 2 different alphabets but mapped to the same keys, you couldn't, without some JavaScript. If you just added those 2 keywords, even if you manually edited or created your bookmarks, one bookmark would override the other and the other would appear empty with no keyword.

The workaround I found was using a bookmark with this code in it (instead of the usual URL):

javascript:(function(){var keywords="%s";var mainURL="https://<URL>/";var searchURL="https://<URL>/<params>-"+keywords;if(keywords==""||keywords=="%"+"s"){window.location=mainURL}else{window.location=searchURL}})();

Where https://<URL>/<params> is something like https://example.org/search/q-.

It's slower and sometimes doesn't work if you type "y" and then the query too fast, especially if you're pasting the query. So sometimes it doesn't work and searches with the browser's default search engine for "y <query>".