I just tried searching "element lemmy" and got the article Lemmy: Fans call for periodic table element to be named after Motörhead frontman
Whereas "element reddit" gives /r/elementchat/
Lemmy is indexed on Google as using the site:
operator will show, e.g. "rust site:programming.dev" gives sensible results, but there's not a way to search across Lemmy. Well, not with Google anyway (Kagi has a Fediverse lens that works fairly well).
The WhatsApp backups are stored in an area of your Google account that you can't access, so you can't really test without a new phone (or deleting all your data).