JFYI, there's no need to install anything. Focus on a search field on (almost any) website, open the context menu, and "Add a keyword for this search". Put a letter or two into the "keyword" input. Profit.
[1] https://blog.mozilla.org/addons/2019/10/15/search-engine-add...
Does this mean I'll have to install an extension to replace each search keyword I have? That would be dozens of extensions, many of them for obscure niche websites.
It just won’t automatically create the URL pattern the site suggests.
However, I was wrong about OpenSearch providing the functionality that the "Add keyword for this search" bookmark feature implements. That feature is completely independent from OpenSearch and isn't going anyway.
"Add keyword for this search" via bookmarks are not going anywhere in Firefox as far as I can tell. This was a false alarm on my part.
No.
> Do they work on Firefox for Android?
Yes.
Again, I think, I'm not sure ;)
I was thinking about OpenSearch custom search engines (being deprecated apparently as another comment notes, these appear on desktop as icons under the search input field "This time search with" and similarly in Android as icons above the on-screen keyboard. These definitely don't sync.
The other thing are bookmarks with the "keyword" property set. These do indeed sync, like other bookmarks.