To be honest, I am not sure if it is ideal to implement this as nobody else seems to be interested in this at this point of time.

was this implemented in the meantime? could also really use this feature.

a solution like this is used in big sites now, like the official premier league website, example: https://www.premierleague.com/clubs/12/Manchester-United/overview

there you can see a mix of posts written by the site (open as regular posts) and also posts where the title simply links to the original article on the club's website (marked with the external link icon after the title)
actually a good way to curate content and fill the site with high-quality content that one person alone might not be able to write himself...

so really hope we have this right now (but didn't see it anywhere in the settings) or get it with v6