In the early 2000s, the biggest social media (though we didn't call it that back then) in Finland was IRC-Galleria (IRC-Gallery). It was originally made for IRC users to upload pictures of themselves and see what fellow IRCers looked like. You'd create a profile, add pictures and tag which channels/servers you were on.
Since there were no other websites like that back then, it was eventually overrun by non-IRC-users and transformed into what we'd now call a more generic social media platform. Something like the eternal September I guess. People started calling the gallery "IRC" as shorthand, which royally pissed off the original userbase. Fun times.
Then Facebook appeared and everyone moved there.
It's still up, but it's more of a historical relic these days. Not sure who, if anyone, still uses it: https://irc-galleria.net/
Wikipedia: https://en.wikipedia.org/wiki/IRC-Galleria
It's weird how different and hyper-local the social media landscape was back then. It's not just that every country had their own thing, it's also that they were all very different concepts and ideas.
Poland's social media of choice was "Nasza Klasa" (lit. "Our Class"), the American alternative was called "Classmates" as far as I know. It was intended as a service that let you re-unite with your old classmates, designed with the way the Polish school system worked in mind. It was used for far more than that though, and was quite popular among kids who were still at school.
We're still in that era with messaging apps somehow. WHile the local alternatives have mostly died out, the world is now a patchwork of WhatsApp, Messenger and Telegram, with islands of iMessage, Line, KakaoTalk and WeChat thrown into the mix. Most countries have basically standardized on one of these, but they can't agree on which one.