Hello @andre7, Welcome to this forum.
Even if the traditionnal way is not so difficult,
you can use the “easy-installer” that is expected to work for a Galaxy s7 on a Linux machine.
(avoid the s7edge that often Sliding hands)
My preference as cheap but fonctionnal /e/phone go to the Galaxy s4 (between 20€ and 50€) interchangeable battery and easy to repair device are other arguments.
Any other supported device is good also