No, it actually could've been much worse: https://www.businessinsider.com/chernobyl-volunteers-divers-...

I don't think so. I'm trying to find some sources, and it seems like all the clickbait articles reference a book by some guy named Andrew Leatherbarrow, "Chernobyl 01:23:40" (and Leatherbarrow is just some guy without any particular expertise). I can't find any justification for why there was a chance that millions would have died and half of Europe was almost rendered uninhabitable. It smells like clickbait bullshit.

I actually agree with you that the article sounds click-baity, unfortunately, HBO has made it so much harder to get good information regarding Chernobyl on the Internet nowadays[0].

Just one of four reactors "melted down". I'm no expert, but I imagine the worst possible is all four reactors literally exploding simultaneously, or one after the other in a rapid chain reaction, or something like that.

[0]: https://www.forbes.com/sites/michaelshellenberger/2019/05/09...

No, nearly all the uranium was contained at Chernobyl. If it had melted down a little faster it could have hit a flooded basement before it was drained. The steam explosion would have distributed uranium dust over potentially thousands of miles.

Do you have a source for the likelihood of that, as well as the likelihood of it rendering those thousands of miles uninhabitable?

I think this theory has been mostly debunked, ironically because it pretty much happened in multiple reactors at fukashima without that disastrous result.

There was no core breach at all in Fukushima.

It didn't fully breach the concrete floor, but it breached the pressure vessels in at least 2 reactors and fell into a "basement" of pooled water, without the catastrophic stream explosion hypothesized for Chernobyl.