If I want a dumb phone for my daily needs, I have to keep a smartphone at home to stay in contact with my friends that are using Whatsapp. I don't really feel free here.

Since Whatsapp isn't a public utility, the people who designed it are free to make it for a certain type of device, with a so-called smart screen. That you feel oppressed because they didn't cater to your very specific need to have it work on a button phone is pretty weird. "feeling free" isn't about having any random whimsy catered to. It requires realistic adjustment to the world of others and their efforts.

Seems like you are very oppressed no matter what. If you want to eat some yoghurt, but have to use a spoon to not get it on your hands, I assume you're oppressed as well.