As much as i like the look of pixel filters I don't really buy it for this. Perhaps you could've made the collectibles, gate, and cat in the ball out of 2D sprites to sell the illusion of it being runnable on Gameboy hardware? Also could do with some more feedback for inputs. Monkey Ball accomplished that by having the controls tilt the world rather than push the ball - a distinction that also subtlely but importantly altered the movement mechanics - but in your case some slight camera tilt or zoom at speed might be helpful.
Viewing post in Super Rolling Cat jam comments
Glad you liked the look, even though it doesn’t look GB authentic.
To be honest, we were not worried at all about making the game look like it could be run on GB hardware. This old console style vs new technology feeling was intentional.
We actually tried to tilt the stage instead of rolling the ball and some slight camera adjustments when moving, but none were feeling good and we just kept it the way that felt better. Due to the time, we had to keep moving on to other features.