I use a rooted phone and afwall+ which uses the underlying Linux firewall. There's also the mobile and WiFi data permissions you can change manually.
For me, root on my own devices is a matter of principle. If an app doesn't work, then I don't want it. In the future I might carry a gimped android device for essential things like train apps if I have to, but then it won't be the device I actually carry in my pocket, it'll be in my bag. Mobile computing is for me.