Good questions!
I encountered some issues when creating releases for recent Android versions, and I am currently working on to fix it, that’s why the game on Android has an older version. (The content doesn’t change between 2.0.0 and 2.1.1, it’s only bug fixes.)
Android versions are bigger because the game engine I use needs more assets to run on this platform than on PC.
Besides these inconveniences, hope you’ll enjoy the game! (￣▽￣)ノ