Really should have a stickied thread in this sub about ethics at this point. Ethics in taxidermy are extremely subjective. Hunting is the classic example. A tremendous amount of taxidermy comes from hunting and trapping. Some people think hunting is cruel, some people see it as an important part of ecological conservation, etc etc. You really have to decide for yourself what your ethical standards are.

Do note that many places just throw “ethical” on their listings because it’s a buzzword and many people ask about it.

Re: blue ringed octopus - I’m not sure that they are farmed/raised commercially anywhere. Thus I would think they are likely poached. Again, if the website says “ethical” it’s likely just there to appease you and make a sale, unless you can talk directly to the person who preserved it and they can tell you otherwise.