Should be able to copy snapshots between regions in Azure Portal
You have a powershell script to do this documented here:
However, it would be much more convenient if you exposed this functionality via the Azure Portal.
Rajani Janaki Ram commented
We are working on a new capability that will allow customers to move Azure resources from one region to another. Could you please fill out this small survey so that we can find out more details on your requirements and assist you with your ask soon :)
Program Manager - Azure Team
Curtis Porter commented
You can move snapshots via the portal if you go to Resource Groups -> Move, then choose the subscription and Resource Group you want to move it to.