The paired TT endings were very similar because they were mostly indirect content gates (eg. I didn't want to force people into shota type stuff just because they liked Martha or saved Bart). I agree the endings were simplistic though (although I wouldn't say I rushed; I'm happy where I left things), and the ones in Level: 0 are definitely more elaborate (at least scene-length, with some involving extended sequences) and substantially different from one another.
Don't worry, she predictably obliterated everyone (though Merchant fought valiantly) once she was actually revealed.
If you (rightfully) found the default path disturbing, there's much happier Hero route (and an Easter Egg meme route) you might enjoy more. Naja and Martha are indeed the cultured choices, though.
Hopefully you'll be pleasantly surprised. The many endings aren't like MGQ/"GOR" games or "Trapped Mansion" text-adventures. The interesting endings do require you to reach the end of the game and your "corruption" (to use your term) stats and their buildup/management matters quite a bit.
I don't want to spoil anything but you're hoping for a long, gradual, debasing corruption I'm hoping to have you covered.