That’s correct. Android is being developed by Google (after they initially bought the company which came up with it), and even if there are Open Source variants which come without any Google Apps or services preinstalled, Android is still an OS by Google.
Explained by a Fairphone employee here …
It seems to me that Sailfish is the closest to being ready to be used as a daily driver.
Another promising effort is UBports (a community continuation of Ubuntu touch, an Ubuntu Linux adapted to be used on smartphones), but as far as I understand, there’s still some work to be done on this to recommend it for your purposes.
For a full overview of what can be done on the Fairphone 2, see oslist (note that LineageOS and /e/ are Android variants).
Well, getting rid of Android on the Fairphone 2 comes down to just completely wiping the phone, which is not too hard to do, but the hard part for an inexperienced user is to install something else then 
.
Instructions on how to install an alternative OS will differ from OS to OS.
Instructions for Sailfish are here …
https://wiki.merproject.org/wiki/Adaptations/libhybris/Install_SailfishOS_for_fp2
A general advice then … a smartphone is a computer. It is a complex machine, and things can go wrong.
In getting rid of Google on a smartphone designed for Android you have chosen a path which even experienced users would consider and evaluate carefully.
Whatever you choose to do … You will be on the safer side of things if you personally know somebody with a general knack for IT stuff (family/ friends/ acquaintances).
We can do all the best we can to help here in the forum, but not everything can be correctly diagnosed or remedied from afar.
If there is nobody you know, perhaps you happen to have fairphoneangels in your vicinity? That would certainly help.
Perhaps you want to reconsider and start your smartphone journey with Fairphone Open OS (supported by Fairphone, see openos ) or LineageOS (supported by the LineageOS community and used by many of us here, see lineageos ). Those OSes come without Google Apps and services preinstalled, and even if they are still Android, they take the biggest chunk of Google stuff out of the phone while still being easily serviceable (there are a lot of people who know their general way around Android).
You can still go hardcore no Google anytime later on .