I have been thinking what it was #linkedin in the pre-crappy pre-influencer era, and it was jobs postings + professional networking + celebrating professional achievements.

If we look to build a "linkedin" in the fediverse, job postings could pretty much be (and it was for many years) forums, so #lemmy or #nodebb could achieve that. #lemmy could even foster professional discussions.

Celebrating could be #badgefed, and professional networking could happen inside #mastodon.

If you create a site with the 3, interconnected, reducing friction (e.g. single sign-on between the three) it could have some traction.

One can only dream.