Is Sunday a low-traffic day on PH? Could launching on that day be advantageous?

You have much less traffic on Sundays than on other days of the week. If your aim is to finish well ranked or even Product of the Day, then Sunday is the perfect day. If your objective is to get traffic, then Tuesday, Wednesday and Thursday will be more suitable for you.

Good question. I'm going to launch tomorrow and I thought it's fine. But what you said is giving me second thoughts.

Why not just try？Low traffic somehow means less product being launch in PH

Not sure.

Your chances of gaining POTD title increases.

Yes.