Seems to work fine on SFOS 2.1.3.7, thanks!
~]$ harbour-cameraplus [D] unknown:0 - Using Wayland-EGL [W] unknown:0 - Module 'QtCamera' does not contain a module identifier directive - it cannot be protected from external registrations. [W] QtCamViewfinderRendererNemo::render:93 - renderer not started yet [W] QtCamImageModePrivate::applyFastCapture:52 - applyFastCapture: not supported harbour-cameraplus: symbol lookup error: /usr/share/harbour-cameraplus/lib/libqtcamera.so.1: undefined sym bol: eglGetCurrentDisplay [nemo@Sailfish ~]$