Yes
Per https://github.com/brave/browser-laptop/issues/3053#issuecomment-244539801 by @da2x:
All search engines, and then I mean every single one of them, have OpenSearch auto-discovery on their home pages and search result pages. Safari and Edge automatically detects OpenSearch-enabled search engines and lists them as suggested search engines in their Preference panes.
This means that every user will find their favorite search engine in the list of possible search engines without having to configure it; they just need to perform one search with their favorite engine and it will then become available. I wrote about this on my blog for anyone interested in the specifics.
I think this is an elegant solution that empowers even inexperienced users to change their search engine to whichever they prefer without technical knowledge. It also exposes many more possible search engines than a browser could reasonably build-in by default. The approach sounds like a good fit for Brave.
Example steps outlined (showing what to look for):
All
All
1. Visit https://translate.google.com
2. Open Preferences > Search
3. Notice that `translate.google.com` was not added automatically as a detected search engine
Nothing happens
translate.google.com should be added to an "Other search engines" list on the page. An example of what this looks like in Chrome:

Yes
Yes
Please pay special notice to the drive-by search provider installation protection feature which work slightly differently in Safari and Edge. Safari also has a fallback for websites that don’t have an OpenSearch Description file (described in the previous link) which can be a … good source for inspiration.
PS: Chrome’s UI is the worst out of the lot here. Look at Edge and Safari instead. Firefox is more discovererable than the rest, but requires a separate search field/icon.
If you guys can't give a simple important feature after so long, you shouldn't make a browser, make a brave extension.
An ad-blocker which can pay the parties.
Although I understand you are renovating browsers, yet there are many extensions I need:
Stylish, OpenSearch, Domain Blocker, Div Blocker, etc.
cc: @davidtemkin @zentagonist for prioritization
Related to #10675?
If OpenSearch is added, I'd love to be able disable it. I understand that it can be useful for folks who don't want to spend the time carefully wrangling their own custom search operators and keywords. I like to meticulously curate those items, and find the automatic addition of other search engines frustrating. Default-on with a settings toggle to disable, IMO.
Brave nearly meets my browser needs, but it's frustrating that I can see the search engine list with shortcuts, but can't add my own. I've used this feature in Opera for like 10 years, so I may have to switch back to it if I can't figure out how to add searches through config files or something.
Edit: Updating lib.devTools.js, app.entry.js, and aboutPages.entry.js (and their corresponding map files) visually adds any searches you modify or add to the search config page, but it isn't hooked into the back end, so typing it in the address bar or setting it as default search won't have any effect even after reboot. So it seems there is not a config file which can be updated.
Happy to report this is fixed with brave-core 😄

But what if we added an "off" switch? brave/brave-browser#867