The idea to build and use the phone OS which doesn’t rely on Apple or Google is quite old. Since the Ubuntu Edge project, there have been several attempts, but nothing which can even scratch those two giants.
The new attempt is here – The Purism project, which is seeking funds right now (link here). The idea is to build a true Linux powered smartphone that focuses on security by design and privacy protection by default.
The device will ship with GNOME Shell UI or KDE Plasma Mobile UI by default. Also, through various partnerships and development efforts in the community, the users will be able to replace it with other UIs!
Once again, here is the LINK. Pledges starts from $20 so you can support it if you like.