As someone who grew up with playing some of the original Gameboy games and someone who has played phasmophobia a lot. I can say you nailed it with the feeling of both, with the atmosphere and how it plays out. The art is great as the game looks like a legit Gameboy game. Also running away and hiding from the ghost reminded me of the game Ao oni. The music needs some fixing as it became unbearable to hear after a short while of playing, though the hunt song was a nice addition to alert the player.
The game is understandably less scary than Phasmophobia but it would be cool if there was some sort jumpscare when the ghost caught you. Dialogue boxes felt very slow and would feel much nicer if it was faster or even instant, I believe most original Gameboy games had instant appearing dialogue boxes but could be wrong. Post game score screen could have more suspense in telling you if the ghost was correctly identified, for example: The Ghost was a....Demon. The post game score screen could also include stuff like the bone, currently it wasn't very clear what the bone did or was for, in Phasmophobia it gave more score.
These are just small addition I believe would improve the game but other than that It felt like the perfect Gameboy version of Phasmophobia. Great job!