Every country or state may be different. I am in Denmark/Europe and we consider cable digging as low risk work in regards to the virus. It is outdoor and the workers are in groups of two people keeping distance to other coworkers.
Our FTTH buildout is not slowed much at all. We do avoid going inside homes which means the installation is not finished. But we can run cable ducts up to the building, blow fiber into said duct and do the fiber splicing at the cabinet end. We also make new backbone and ready new areas for FTTH.
All of this means we also see the usual amount of damage done to our stuff from other parties. In this case we will do home visits to get someone online again. Internet is considered critical infrastructure, so we must do so.
Regards
Baldur