I have this website that fetches pages' meta info (links, title) and their main content from some predefined external websites (Sources), stores them in the database (as posts) and shows them to the viewers based on category/source. So if a viewer opens a permalink in my website, the permalink doesn't redirect to the source website; it loads the content in my own website instead.
But recently (because of right issues and many other reasons) I decided to omit the main content and redirect the permalinks to their own sources. So my category/source pages include only a thumbnail (if any), a title, a short description and the link to the original page in its source, for every post.
Here is the problem. Search engines like Google will not index/score my permalinks, because they're not actual pages (they redirect to the original source page).
Is it good (SEO-wise) to use an intermediate page that will show up after opening a permalink and before auto-redirecting to the original source page?
Is there any other way to make Google index my permalinks and still be user-friendly?
My website serves over HTTPS, but most of its sources are served over HTTP. So I can't use