As detailing hobbyist, mine has never seen such fading as my paint is always protected.
IMO, a better & safer (for the paint) way to do such restoration is to use a compound if there are deep scratches, then polish to recondition the paint to bring back the deep gloss & remove fine scratches, then seal/protect using either wax or sealant.

If you notice that paint transfer, it means that your clear coat is gone. It seems like you've started with a very strong abrasive at 1k grit then moved to 3k. Compounding could've removed the scratches in most cases without hurting the clearcoat

While this makes sense, the clear coat had already been damaged. If I had known the door handles of all things were Fisher Price, I wouldn't have let them go unprotected :) there certainly are better ways of going about this, I was just providing a cheapskate backyard mechanic way of doing it. The 1k grit probably is unnecessary, but I tried just using a buffing compound and got nowhere so I decided to go deep.

Thank you for the input! I'm by no means a detailing professional and am always open to advice.