You can do almost exactly this with keyword bookmarks. The only change is that you need to put the “keyword” at the start of the URL. So @l linux rather than linux @l.

Create a new bookmark with these settings:

• Name: Whatever you want.
• URL: The search query you want with the text replaced by %s. For example https://kagi.com/search?q=%s+site:https://lemm.ee.
• Keyword: The tag you want. Such as @l.

Now you can type @l foobar in the URL bar and it will go to https://kagi.com/search?q=foobar+site:https://lemm.ee. (Or whatever search engine you have configured.

Keywords can also be used for non-search bookmarks and javascript bookmarklets which are very convenient.

This is one of the features in chrome that I wish Firefox would implement.

You could try system wide macros. If you type @l, macro deletes last 2 chars and types lemmy