It’s an interesting question, what to do with your $. On one hand you could buy a service or product, the other you could buy the knowledge. Few years ago I completed a degree in Business Information Systems. The music industry is an information system. If there was a roadmap for a music career, I would buy the knowledge, then the product or service. Knowledge is almost free. Just takes time to pull it together.
I use them and a lot of artists I know use them. Their main method of promotion is probably influencer marketing so you may not find stuff about them online besides videos from creators