Thats fair, ironically I was playing Sonic Adventure later for footage and having a blast, but agree those opening areas are a slog. I say ironic because the worst part about Sonic Adventure for me are the open areas clearly inspired by Mario 64.
Those and Big's levels.

I think it may actually be FM Synth, albeit augmented by the Mega CD's additional PCM audio channels. I may have top pop the disc in a CD player to be sure 😅

Cheers mate. I did see the magic, as I said, the opening levels are definitely magical, its just that beyond that I dont think its an enjoyable game to play, but thats just me.