There are a couple of browser extensions for the other place that show you what subreddits a given URL are posted to. If you’re looking for discussion about a current link/page/site, it’s very handy. Also, if you’re submitting links, it’s helpful to show where a given link has already been submitted and when.
Searching Lemmy instances can be daunting. An extension like this would be amazing.
Maybe you could have a setting where you indicate 2-4 instances you want it to always search. A lot of instances are like mine, just made for one or a few users and aren’t going to host a lot of content.