Samsung Galaxy S5 Active root issues/no access to computer. model# sm-g870a topic

I don't have access to a pc and every single mobile root option such as towelroot, framaroot, kingo root etc. etc. Fails to root am I just SOL to the idea of being able to root?

SM-G870A with SM-G870F ROM topic

Hi everyone,
is it possible to put stock rom from european version of S5 Active to AT&T S5 Active? Do I have to change kernell as well, or just simply flash stock rom from G870F? Thanks