In order to fit the screen, the screen area needs to be widened.

I used a file for that:

I took the tetris cartridge apart and cut the lower part around the line as good as possible. I also cut down all the posts inside the cartridge. The cartridge was so brittle that it literaly fell apart when I cut it, but that is OK because you won't see that when it is slotted in the gameboy. I then glued the two halves together with hot glue:

Most of the battery compartment has been removed in the same way So the raspberry pi fits inside:

Then I widened the charging port with a file too:

Then you can glue in the charging port: