If you are approached by these publishing companies in the comment section of your book, I'd advise you to think keenly about it. I'm not saying it's not legit, neither I'm I saying you shouldn't consider them. Only, success does not come to you, you have to go and seek it.
Also, we have a Swahili saying that goes 'Chema Chajiuza' and it directly means whatever is good sells itself. I don't think if those sites were as good as they sound they would be advertising that intensely.
If you wanna try them, go ahead but just ensure you don't fumble your story in the process.