I'm much more convinced that you're competent in the field of forensics. But I still don't think suspicious network traffic can be categorically defined as a 'device breach.'
For all you know, the traffic you've observed and deem malicious could just as well have been destined for Apple servers.
They said upthread that they had blocked 17.0.0.0/8 ("Apple"), but maybe there are teams inside Apple that are somehow operating services outside of Apple's /8 in the name of Velocity? I kind of doubt it, though, because they don't seem like the kind of company that would allow for that kind of cowboying.
Apple traffic goes to 17.0.0.0/8 + CDNs aliased to .apple.com, which my egress router blocks except for Apple-documented endpoints for notifications and software update, https://support.apple.com/en-us/101555
appldnld.apple.com configuration.apple.com gdmf.apple.com gg.apple.com gs.apple.com ig.apple.com mesu.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 swscan.apple.com updates.cdn-apple.com updates-http.cdn-apple.com xp.apple.com
There was no overlap between unexpected traffic and Apple CDN vendors.