The YouTube sponsor situation is actually crazy, I think 100% of them have turned out to be either scams or just very overpriced. Even ones that sounded reasonable, like Ground News, and VPNs.
like I get ads for Lexus -- I'm in a big city and don't need / want a car, but like Lexus is a real brand, basically Toyota.
Some no-name VPN or idle-game app is an immediate "I will actively avoid this, froever"
Where could that possibly end up causing problems?
Also it doesn't actually show you the news. It just shows you links to news sites that you need to be separately subscribed to if you want to read them, so in that sense you're just not getting the product you probably thought you were getting (access to balanced news), so it's a double scam.
There's video essays about this on YouTube of course since that's where Ground News was mainly advertised.
If what you say about the audience composition and the general background situation were at all true, it would be impossible for them to find sponsors, because it would require YouTubers who depend on appealing to a partisan audience to deliberately seek to betray them. And if what you say about the product were at all true, it would again be impossible for them to find sponsors, because none of the YouTubers would be willing to endorse the product.
If anything, the problem with Ground News is that they buy into the same categorization scheme of the news that you do, perhaps with a different bias but the same clustering and same false impression of a single-dimension spectrum.
You deliberately misunderstand the point about advertising audiences, that is not how advertising audiences work, at all. The point about influencers rejecting shady sponsors is also false, and circular. All evidence suggests they mostly accept sponsors who offer money.
If Ground News "bought into the same categorisation that I do" there would be literally no reason for it to exist. It exists to change the categorisation you buy into.
there is the illusion of "balanced" or more in the know but they are no more balanced than any other curator, and in many cases try really, really hard to present a mixed view of something that is otherwise inexcusable.