I'm guessing you already disabled personalized google ads on those devices?
Google aims to show you relevant ads based on your interests. Use this tool to select interest categories so that the ads we show you are more related to your interests.
adssettings.google.com
google will probably still collect the data, but won't send targetted ads to those devices/browsers
Also if you have unlimited data, don't do those searches on wifi. That might help.
Even limiting all the app rights and using private browsing doesn't stop the ad services...