Biblaridion is a YouTuber who engages in linguistic and biological counterfactual speculation. His ongoing series on the evolution of life on an alien planet is quite interesting, and as far as I can tell from a layperson's perspective, well-researched. I find it an interesting example of worldbuilding from complete scratch: coming up with a planet and then imagining how its biosphere would develop over billions of years. Five episodes in he has ended up with a fairly complex ecosystem.