I wouldn't be surprised if Alphabet has used data from all these sources all the time.
That's actually the reason I don't use gmail except for registering Android, or use google calender, or google search except occasionally. I have my youtube account separate from my Android, and I don't allow any cloud services, like photo or any other storage or sync services.
The power Google can gain from using these things in combination is huge, just like Facebook influenced the 2016 US presidential election, Google/Alphabet could use this for both political and financial gains to an enormous degree, that would have been completely unheard of prior to Internet becoming widely used.