If the content to import is in another database that you have access to (via custom programming), then it is technically possible to extract data from the source database and create pages/posts from that data/content into your WP site.
See my answer to Automating Page Creation . The link to https://developer.wordpress.org/reference/functions/wp_insert_post/ contains the WP code needed to create a page/post.
If the program was smart enough to only grab ‘new’ data (assuming that the source data had a ‘publish-date’ type field), then you could run a WPCron job to periodically grab ‘new’ data. Your program would check to ensure that the content wasn’t previously created by a previous WPCron job.
Customize programming needed, with data access to the source data. But, technically possible, IMHO.
Good luck!