I've never used it, but my understanding is that something that does this is considered a "killer feature" of Supermemo. It has a mode that lets you read text (via a PDF viewer) and lets you create flashcards as you read in some kind of semi-automated way. Or something like that. Like I said, I never used it.
+1 SM is really interesting. Supermemo.guru (URL) is a fascinating resource written by a fascinating person (the creator of Supermemo), but the software is so unusable that it immediately shoots itself in the foot (or head). I don't think anyone should ever use it, but people should take away from it interesting concepts that they can use when writing new software.
No, not PDF, only HTML. There are community companion programs like SuperMemo Assistant, that enhance SM, but it‘s all fiddly.
I paid for two SM versions and went back to Anki. It‘s very idiodyncratic, the user interface is atrocious (in the latest version it finally, finally added thumbs up/down icons for grading the answer —- before that you had to remember whether 1 is good and 5 is bad or vice versa).
SM is fascinating (including task management, sleep cycle tracker etc.), but it‘s held back by its technological choices (only support for Edge or IE, and Edge only in the newest version), and for incremental reading you‘ll be mostly ingesting Wikipedia articles, because PDF isn‘t supported.