The game has a really sweet feeling! It is almost meditative walking around on that island making friends with the wombat.
I overall like the music, it has some quirky randomness to it.
Like you wrote, it's obviously not a finished game, but it feels like you can build on top of it and go in many different directions. The wombat is a cool sidekick and I look forward to seeing how the player and the wombat can interact more.
Perhaps the wombat needs more than just one apple to be befriended? Perhaps they need rewards each time they found a coin, at least until X coins have been dug up?
The graphics is spot on, it shows that you really know what you're doing in that department.