[[wikilinks]] and #hashtags as a portal to cross site search

[[wikilinks]] and #hashtags could act as snippets for custom searches on various platforms. I’d like to be able to either click on a link or possibly right click and be presented with the ability to search that term (or nearby terms) on a variety of different platforms or trusted websites. This could be a useful form of personal search that allows me to find things within a much smaller space of knowledge I’m aware of. Sometimes the serendipity from the wisdom of the crowd via major search engines like Google, DuckDuckGo, or Bing may suffice, but shouldn’t I be able to more easily search a trusted personal group of hand curated sources?

Platforms like Wikipedia and Twitter already have these patterns as links to resources within themselves, but why couldn’t/shouldn’t a browser or browser plugin allow me an option when clicking on them to go to other resources outside of the expected (narrow) search provided? Perhaps I’m in my own wiki and a redlink [[wikilink]] obviously doesn’t exist on my site. Why shouldn’t I be able to click on it to go to another source like Wikipedia to find it?

These search resources can still be larger platforms like Google, Wikipedia, and Twitter, but could be subspecialized to include Twitter users I follow, smaller wikis I use (including my own), websites of people I follow in my feed reader or social reader (by searching on categories/tags or even broad text search). I should be able to easily define a multitude of resources for each custom search using common standards. This affordability could give me a much more refined and trusted set of search results, particularly in a post-fact society.

One could go further still and highlight a word or words on one’s browser screen and use these as a custom search query.

If built properly, I ought to be able to create “playlists” of sites and resources to search for myself and be able to share these with other friends, family, and colleagues who may trust those sources as well.

I’m curious what others think of this idea. What should the UI look like to make it clear and easy to use? What other things might one want to search on beyond plain text, hashtags, and wikilinks? Am I missing anything? What downsides or social ills might this pattern potentially entail?