Hello! I’ve played the game a decent amount in my life and noticed I would actually place on the leaderboard if I were to submit a run. Problem is, I’m not sure whether a Retro-Bit Retro Duo is legal to use based off of the rules. Thank you!

Unfortunately not. The rules under the leaderboard list approved hardware and emulators for speedruns. Retro bit duo is not on the list of approved hardware.