I don't know that much about Linux but isn't Apple based on that? If you went pure Linux wouldn't you have more freedom?
You have to turn off SIP to change those icons. I don't know of any other alternative. And turning off SIP (as described in one of my links above) requires booting off the recovery partition and entering a command in terminal. If that's not your cup of tea, you'll either need to find someone to do it for you or settle for the icons that Apple has given you.
Theoretically yes, "pure linux" gives you more freedom. It also removes most of the safeties that prevent you from shooting yourself in the foot, and makes things significantly less user-friendly, requiring a much more in-depth knowledge of the operating system to use it.
It gives you freedom like going out into the middle of the jungle gives you freedom. Yes you can do anything you want, but you might fall into quicksand or eat a deadly berry. There will be no internet let alone TV or mail. And making your own thatch hut is no picnic.
