I use the Flipboard application for news and related stories. Lately the advertisements have become video based and very distracting. I use the flipboard application in both Android and Windows on the same network as Pi-Hole.
as a start you could find out the ip of your mobile device and filter on this ip in the log.
Load the flipboard and record the time.
Try to see what is send to your ip (mobile) in the log during that time.
There is no real document how to determine the wanted domains and the unwanted domains.
Its a little bit try and error, but if you block the doamins serving the ads and the flipboard is still working, be so kind to put these domains in the post?
There is about 40 lists of pihole compliant list files tou can add to the filter lists in the gui.
I could send you what I am using, but htis ifo you can also find here in this forum....