AFAIK none of current Mikrotik devices come with fiber ports built-in … the plethora of devices, which eventually support FO, require installation of appropriate SFP/SFP+ module. Vast majority of single-mode SFP modules are intended to be used with blue optical connectors. And as I mentioned, finding an appropriate SFP/SFP+ module, which will both work in your provider’s optical network and with Mikrotik devices, is far from an easy task.
Optical network providers often use their own “optical to UTP” converter as official optical network terminal (ONT). Those are not simple physical layer converters, they also allow some monitoring/management functionality to the optical network owner, etc. Replacing that with 3rd party hardware calls for trouble … and you dhould do it onky if you know well what are you doing (and what for) … IMO it’s most often not a wise decision.