Expanded Default Search Engines

[beamo]

You should be able to set any website with a search function as your default search engine like you can in Chrome instead of being confined to the small list of search engines that Firefox provides you.

[Jon]

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[Jon]

Some potentially related ideas here:

Search engine management - add and remove search engines 

Adding custom search engines 

[S2000]

I think it is already supported:

https://support.mozilla.org/en-US/kb/add-or-remove-search-engine-firefox