You should change your materials shaders from standard to diffuse or diffuse bumped to remove specular reflections because PSX games dont have those.
you might also want to remove realtime shadows entirely.
I was thinking about but personally i dont want it to be fully PSX, i was going for a weird mix of PSX and modern graphical stuff for a sort of different mix of styles and a strange uncanny effect compared to all the other PSX games on itch that stick to the PSX style fully! But thank you so much for your feedback either way!