Google's John Mueller recommended that when it comes to your Google News sitemap file, try to use one sitemap file. John said it will result in Google being able to "crawl it faster" and Google does not "have to consolidate signals" he added.
John did say that you can use multiple files, if they are "for non-overlapping sections" he said that is "less of an issue."
The specific help document does say you can "add up to 1,000 full URLs to include more, break these URLs into multiple sitemaps, and use a sitemap index file to manage them. Use the XML format provided in the sitemap protocol. Do not list more than 50,000 sitemaps in your sitemap file. These limits help ensure that your web server isn't using large files." So yes, you can have multiple files but try not to have the same URL listed in multiple Google News XML sitemap files.
The help document does warn to "update your current sitemap with your new article URLs. Do not create a new sitemap with each update."
The news sitemap file should only include URLs for articles published in the last two days. You can remove articles after 2 days from the News sitemap, but they remain in the index for the regular 30-day period. I personally do this, to keep this sitemap file small.
Here is John's tweet:
I'd try to just use one sitemap file for News. We can crawl it faster, & don't have to consolidate signals (same URL w/different meta-data in sitemaps?). If they're for non-overlapping sections, that's less of an issue.
— 🍌 John 🍌 (@JohnMu) August 3, 2021
Forum discussion at Twitter.