The closest thing I could find for the registering without verification claim was a Verge article [1] about people's Fortnite account being taken over after clicking a link that was sent to them. If you have a better source please do share.
EDIT: Source has been found, apparently store didn't initially send a verification email so anyone could use any email[4], this has been fixed though. I could find no source for the claim that this affected millions or thousands of people.
As for the claim that they were "scanning your pc for everything", that is just completely wrong. According a few articles [2][3] they were reading your steam friends list after getting permission from the user.
[1]: https://www.theverge.com/2019/1/16/18185398/fortnite-player-... [2]: https://www.slashgear.com/epic-games-store-isnt-spying-but-d... [3]: https://www.pcgamer.com/epic-steam-data-reddit/ [4]: https://twinfinite.net/2020/09/crysis-remastered-ray-tracing...