For Apple users: I looked up what URLs need to be whitelisted in order to avoid issues with iCloud, iTunes, etc. and to make things easier, you can just copy & paste this two commands to add all the Apple Provided URLs.
Nothing shady here, all this URLs can be found on Apple's support website:
pihole --white-regex *.push.apple.com *.itunes.apple.com *.apps.apple.com *.mzstatic.com *.amazonaws.com *.cdn-apple.com *.digicert.com deimos3.apple.com *.symcb.com gg*.apple.com *.symcd.com mesu.apple.com
pihole -w albert.apple.com captive.apple.com gs.apple.com humb.apple.com static.ips.apple.com tbsc.apple.com time-ios.apple.com time.apple.com appldnld.apple.com gg.apple.com gnf-mdn.apple.com gnf-mr.apple.com gs.apple.com ig.apple.com mesu.apple.com ns.itunes.apple.com oscdn.apple.com osrecovery.apple.com skl.apple.com swcdn.apple.com swdist.apple.com swdownload.apple.com swpost.apple.com swscan.apple.com updates-http.cdn-apple.com updates.cdn-apple.com xp.apple.com itunes.apple.com ppq.apple.com lcdn-registration.apple.com crl.apple.com crl.entrust.net crl3.digicert.com crl4.digicert.com ocsp.apple.com ocsp.digicert.com ocsp.entrust.net ocsp.verisign.net gdmf.apple.com deviceenrollment.apple.com deviceservices-external.apple.com identity.apple.com iprofiles.apple.com mdmenrollment.apple.com setup.icloud.com vpp.itunes.apple.com