Niches currently have tabs: Featured, Trending, Quality and Recent.
We could have a tab in which the content is human curated to some degree.
This idea was born from the need to mitigate the Team's qualms about the 'centralized' nature of human curation. The best choice is usually to let users decide what they want. So offer them both algorithm curation and human curation, and let them choose which tab they prefer. You could have the initial default be the algorithm curation tab, if you feel that's more appropriate, but allow people to change the default in their preferences.
This new tab could be called 'Curated', and could include featured content, sticky content for posts of enduring utility for the niche (such as the niche introduction post), and even a community chosen post that gets replaced periodically. This community chosen post could be something a niche follower gets to vote for, separately from their normal upvote. This is useful because a user's upvote does not necessarily mean they feel a post should be featured. Explicitly voting for posts to be featured could seriously boost the appropriateness of what gets into those slots.
If there is a sense that this creates too many tabs, I would suggest taking a hard look at whether the existing Featured and Trending tabs both need to exist. Since the Curated tab would have featured posts, Trending might be enough for the algorithm-curated content. This would be truer to the words being used: 'trending' literally implies classification based on popularity with the crowd, whereas 'featured' has a connotation of considered selection by the establishment.
There is a wide gamut of possibilities for restricting how much curation takes place in the Curated tab. You could allow it to be fully curated (since it is now in its own cubby hole), or you could limit the amount of content pieces moderators and owners could feature in a week, and the duration of the featuring. You could allow the top five or ten pieces to be human curated, then have a line below which the pieces are ranked by the algorithms that currently operate on the Featured tab. You could charge a nominal NRVE fee that owners would have to pay for featuring content in this tab, increasing the demand for NRVE.
Lastly, to address concerns previously expressed by the Team that any curation in niches might create dangerous overlap with Publications, please take into consideration that no brand in existence would choose a niche over a Publication: brands expect nothing less than total control over who creates their content and which of their pieces get to represent the brand. Most insist on editorial control over the content too. None of these things are possible with niches, and a small degree of curation in niches would do absolutely nothing to change this.