Filter multiple different main queries on custom pages

You can’t alter a page query via pre_get_posts (in any fashion I’ve tried) to something other than a page query. If you look at the generated SQL, it’s trying to query all your post types for a pagename of new. If you set pagename to null, it’ll return posts, but it will disregard any taxonomy parameters you try to set.

Even if you could successfully alter the query, it would no longer be a page and wouldn’t load a page template.

I think the simplest way to handle this is to just create a new query in your template via WP_Query.