Sure! I'll look at the docs to see what's the best way to add a fullscreen toggle from the Godot side. When I tried adding itch.io's built-in fullscreen toggle, it was interfering with input.
In the current version, the speed level increases every 5 lines cleared. The early speed changes may be a bit subtle, so I'll think about adjustments to the starting speed. Although the start of the game might feel relaxed, the mid-game and late-game speed is quite brisk!