Looks like it is possible. I got an answer here:
https://answers.microsoft.com/en-us/msoffice/forum/all/can-i-ghost-publish-a-news-post-on-someone-elses/7d8b0e05-b255-4c12-ae3b-4b04ab30c529
Hello, Nik
Per your description you want to post the news on behalf of the other users in organization.
Please follow these steps to create a news post and set the author.
On SharePoint site select +New > News post.
Choose a template and click Create post.
Type the news’ name and remove the profile.
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In this field type a name or email of the user this news post must be on behalf.
Select Post news if you want to publish the news on the page or Save as draft if you want to continue your work with this post later.
Here is a fast result of creating a news post on behalf of the test account:
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I hope this information was useful for you. If my understanding is not consisting with your scenario please post back to us and point that.
Best Regards,
Igor