That is a unique-looking bike.
The seat stays appear to be bolted on top and bottom, which is how a PO was able to fit a belt without cutting the frame or using a split belt. That it has track ends rather than a dropout suggests this might have been a track bike in its early years.
However track bikes generally don't have brakes for track use. It is possible the same PO fitted the front hub brake (wise move) and uses the fixed gear rear hub as the back brake.
The belt drive system is a relatively recent addition, and I guess this frame was selected because of the rear stays. I can't find a "coronado" crank with belt drive, so its possible this combo is an aftermarket replacement of traditional chainrings with a single drive belt spindle.
The rear hub appears to have a "pull chain" hanging from the side and tied by string. This could be a way of making an IGH into a single speed ? Seems dodgy to me, I'm not sure if an IGH would like being locked up for rear braking, or more likely this bike only has a single brake and the rear coasts.
The head tube angle looks very "reclined" compared to more modern designs. I bet this bike is easy to ride no-handed due to the slack angles.
Obviously the handlebars are a replacement - this bike would have had drop bars or track drops originally. The saddle is definitely much newer too.
Lastly, the tubes appear to have a Woods or Dunlop valve. These have become less common globally, other than China and the Netherlands. I would also suggest looking closely at the tyres for dry rot and cracking, for safety, they don't look new.
All in all, sweet bike and you'll enjoy riding it. If it were me I'd fit a rear brake, connect the IGH to a shifter, and possibly go back to drop bars.