You really shouldn't be surprised that most "news" organizations skew left. That's how things have been for quite some time. The difference is that many don't even pretend to be objective anymore. And, since they usually hang around with others of like political slant, they're completely unaware that anyone would feel differently.
Now, before you jump down Roku's throat about the ads, consider that they're getting paid by Newsy (and all the other advertisers) for those ads to be displayed. Just like when someone is watching cable on their TV, or listening to their radio, or using some other entertainment device. Newsy (and others) give them money in exchange for the ad space. Capitalism at work. Which is kinda funny when you think about it: a left-wing organization advertising using capitalism.
There are plenty of things being advertised that I don't like. I can filter it. Roku still gets to report an ad impression, but I certainly don't click on it, mostly because I ignore it. In fact, when they show something I do want to follow through on, I often miss it because I don't even look directly at that section of the screen.
Roku Ultra (4660)
Apple TV (5th gen), TiVo
Roku boxes from every generation.
Apple TV (2nd, 3rd, 4th gen)