At a local level advertising probably doesn't corrupt the journalism simply because there isn't very much of it.
https://inn.org/members/ http://www.lionpublishers.com/members/list/
There are thousands more that are not members - simply professional and entrepreneurial journalists trying to make a living doing what they care about.
One of the businesses is an auto shop. If that auto shop is doing something like re-using old oil to save money on oil changes or some other shady tactic would the hyperlocal news go after them?
I’ve never seen investigative journalism out of my hyperlocal news, it is all just community news about upcoming events and the like.
I could be mistaken but your links don’t make it clear to me that any of these hyperlocal organizations are doing investigative journalism. My hyperlocal outlet certainly doesn’t.
The ones that do exist appear to be non-profits relying on donations (e.g. aspenjournalism.org / birminghamwatch.org) that don't run ads and give a strong impression of being run by one or two people.
I'm really unconvinced that this is a significant industry let alone one that is supported by ads.
At a local level advertising generally does not corrupt the journalism. At the local level, it's community oriented where the journalists are genuinely interested in giving a voice to advertisers as well as informing citizens. It's a more positive ecosystem than what you see on the national level.