That was a big complaint during the 2022 migration. And it’s something that’s basically available on every fediverse platform not called Mastodon. I wish that fact had caused more people to actually check out those platforms, rather than further entrench Mastodon as the core of the fediverse.
Search will never search non-local content. That’s not how search works anywhere. Even Google is searching local content.
That’s what search engine spiders do. They create local profiles of websites that end up being sorted and searched.
We have to give up on the idea of having easy and direct access to the whole of thw fediverse. Fefiverse sites don’t even know about every other fediverse site, and they never will.