Steel commuter recommendation with belt drive for low maintenance?

Hi all
I'm in the market for a new commuter bike. Willing to spend a bit more as I will use it daily but also looking for low maintenance hence was looking for something with a belt drive.

Requirements would be:

• Steel frame
  
• Belt drive - or at a minimum a 1x (will need gears to get up hills where I'm at with load)
  
• Hydraulic disc brakes
  
• Bike rack
  
• Prefer gravel bike instead of mountain bike setup
  
• Rear rack for panniers
  
• Dynamo front/rear lights
  
  

Was looking at a Fairlight or a Surly frame but they don't have a belt drive.. any other suggestions? budget would be +/- 3k

Thanks