[spoiler warning]
brought the starting block out to try doing something with that before i realized it’s possible to get the “L” free. brilliant game.
yup :) [more spoilers below]
after splitting the player character in half you can get split of the halves along the other direction to make it quarter-sized. then you can get the other player piece to be in the starting room pushing out the block, while the quarter-sized piece is waiting inside the upper-right corner of the triangle. then you can move the block up.
if you also used the moving block earlier to slice the quarter-sized piece diagonally, you can then use that to move the block out into the center area.