Cooking with any plastic is a dubious enterprise, because heat encourages potentially harmful plastic compounds to migrate out of the polymers and potentially into the food. But, as Andrew Turner, a biochemist at the University of Plymouth recently told me, black plastic is particularly crucial to avoid.
In 2018, Turner published one of the earliest papers positing that black plastic products were likely regularly being made from recycled electronic waste. The clue was the plastic’s concerning levels of flame retardants. In some cases, the mix of chemicals matched the profile of those commonly found in computer and television housing, many of which are treated with flame retardants to prevent them from catching fire.
Generally you don’t need to worry much about pots. If you have a problem of things sticking in them while cooking I guess it would work though. I have a coated cast iron pot for proper cooking, so I rarely use my stainless steel one for other things than boiling stuff. No need to season them for that.
It needs to be done to stainless steel frying pans. If you go for a stainless steel frying pan you probably want to get a five-ply one, which means that there are two layers of (usually) aluminium inside the pan helping with heat distribution. Once you have that it’s a great alternative to cast iron - I find it easier to deglaze because the surface is shiny. But in its own right heat distribution in stainless steel is not good enough to make for a good pan, and a good stainless steel frying pan comes with a bit of a learning curve.
I guess it’s the same thing with carbon steel as well, but I have no experience with that.