> many pretend that they are indie content creators when they are just the marketing / growth hacking arm of the sponsor.

Just curious, but can't they be both?

I don't know those channels. The one I regularly see are very diverse in their partners, and usually the content is unrelated to the promotions. But overall those promotions are negotiated based on viewer counts, and at a certain size, they are more valuable than earnings from ads.

Absolutely can be both. And often they make it clear: like cappello army does. But then there are the more shady ones where it's less transparent