Be sure to select the right install package for your needs.
Open GApps comes in different packages, which install different amounts of Google stuff. You can click on the link icon next to the package name to get more info about the contents of a package.
A common use case would be to run just a few specific Google-dependent Apps, which would need only basic underlying Google services and the Play Store. In such a case, the “pico” package would be sufficient, and you wouldn’t get any “visible” Apps apart from the Play Store this way.
At least this should limit tracking to other things built-in in Android. Can’t find a good summary about all the other stuff “phoning home” quickly right now, but there should be something out there …
For a mostly Google-free phone, that would be the logical choice. Here’s more info …