Hello @ all
if you have installed firmware remove it if possible.
The install Process check that /usr/include/machine is empty.
then check that the directory /usr/include/machine is empty.
If not clean it.
I think this part is way off and probably all the way into "bad advice".
Cleaning /usr/include/machine is wrong, and fw_update seems completely
unrelated to either the contents of the C includes or building WG.
You didn't have the compiler installed which what was causing your issues
with building wg and I think that's it, nothing more.
May the most significant bit of your life be positive.