Congratulations on completing the jam!
The concept is solid, eat green dice to extend your snake, red dice to shrink. However, there does need to be some balancing to this cycle.
First off, the dice respawn as soon as they are eaten allowing the player to fully control the length of the snake. This eventually leads to the least-fun version of this game which is the player staying at the shortest possible snake and easily navigating the space to collect whichever number they want. I did this up until 500 then I got too bored to continue, but there aren't any feedback loops there to make it difficult eventually.
What I would suggest is to rig the dice. The most fun for the player is most likely making quick decisions and properly routing a long snake through the grid. At the beginning, or at least while the player has a short snake, the dice should always fall to extend the snake and push the player to use up more of their space. As the game goes on you then reach the opposite end of this loop where the player's snake becomes too long to manage and will eventually force them to lose. To fix this you can add in relief in the form of powerups and negative dice to bring the snake length back down. With both of these feedback loops, you can now adjust the difficulty over time by changing the target length of the snake and building tension with longer and longer snakes. Add in additional difficulty through speeding up the snake, and other environmental pitfalls and you're well on your way to a full game!
Great work for 48h, congratulations once again on completing!