Tried this, the results are very bad.
It shows me some random mod-logs and weird links, nothing relevant I search for (posts or communities).
My custom lens with just 10 URLs added (since we cannot add more) show way better results - but still can be greatly improved.
URLs used:
kbin.social, fedia.io, readit.buzz, lemmy.world, lemmy.ml, beehaw.org, feddit.de, sh.itjust.works, lemmy.one, lemmy.ca
Best would be, like it was mentioned in a previous reply, having an instance crawling through everything and the possibility to set a "home instance" which automatically shows the result in the instance the user uses - but still with a link to show the original instance similar like it is with URL rewrites.