RSS feed for paywalled website

Hi. I have the pro version with the feed to post and full text features. When I try to add a feed from a website that requires you to log in (e.g. paywalls etc), however, I only get the excerpts and not the full article. Is there a way to solve it for such websites? If we have a valid login for example, via API? Or any other solutions to generate a valid RSS feed that we can bring in via the plugin and get the full text?