1- Yes, the camera needs it. When I was on stock P9a, I debloated a lot. Without those pixel services the camera gave an error.
2- use as much as possible from Fdroid. Only use Aurora if there is no alternative.
Example: I use Hibernator, because Hail and Superfreezz dont work for me. And I dont want Root. So I accept some trackers in Hibernator that get blocked by Iodé / Nextdns anyway. For last app I use Hagezi Multi Ultimate filter.
But not much is blocked. Seems like Iodé browser with max protection is doing a great job.