Nice work! Loaded this onto my Gameboy Color via Everdrive, my high score is 70. I ran into a few issues.
The movement seems a little stuttery - the jumping movement specifically seems to be very stuccato, and it's not possible to duck (pressing down results in jumping).
I enjoyed the graphics and the way the highscore was implemented. The gameplay was not as faithful to the original as I would've liked - jumping results in your character teleporting into the air with a gradual fall. There are flying enemies which appear as frequently as cacti - you just don't jump to avoid those.
It's impressive that the game got ported in the .gb format, but I would hold off on a hardware release until you've tweaked the feel of the jumps. In the original, the duration you hold down A changes the duration of the jump; ducking was used to avoid low-flying enemies.
The main, most glaring issue which makes this unpleasant to play is the lagging frames. The cactuses seem to randomly speed up and slow down on each frame, and because there's reduced control over the jumps it makes the difference between a high score and frequently dying on the second cactus.
If this is an issue with the gameboy hardware, it could be addressed with gameplay by making it more forgiving.
Thanks for reading!