My ISP (Bezeq, in Israel) has a list of approved SFP modules, and they can supply the modules themselves, but there’s no issue using your own router with their SFP module
Of course this will differ with your provider, you should check with them, though be aware the level 1 customer service reps might not know what you’re talking about
/bin
is symlinked to/usr/bin
, so it doesn’t matter.