I find it interesting that you took the classic advice of "just use Box2D" for a 2D platformer and it worked well for you. It doesn't seem like your game using anything much more complex than basic box vs. tile grid collision and doesn't use any of the advanced features of Box2D. No complex constraints, rigid body usage seems simple or non-existent, etc. I could be completely wrong about that though, this is all speculation based on the video and your devlog.

What kind of issues were you running into with implementing tile based collision? Was it intersection tests with slopes? Performance issues? Stability (crashes)?