Don’t worry about wd-40, that’s mild and won’t hurt your finish.

I, myself don’t use simple green on my bike. That can hurt your finish and can corrode, or embrittlement of metal if not used and cleaned up properly.

I oil my chains, I’ll use wd-40 as a wipe down cleaner, sometimes. Every once in a while I’ll do a solvent bath of the chain. The bath, and gravity, gets most all of the uck. You may still need to lightly brush some crud, some compressed air, a second bath.

I usually don’t clean a chain until after it’s been used in rainy weather, or gritty conditions.