Update user permissions for nodes

I found a 2 year old topic here which states that Lithium does not provide a way to get permissions via API. So I assume there's no way to update permissions either, but I want to confirm.

Our use case is that we have ~1000 nodes which we need to update the default user permissions for. We can't update it at the community node, because the nodes aren't using the defaults, they were changed to explicit deny.

It will take a lot to go through this may nodes, so we're hoping to find a way to automate it.

Thanks!