Most likely he is in a corrupt nation. Instead of just hiring someone else. Please help your developer. Money has power in corrupt nations. Help him. War is deadly, I do not think he will be as safe as you think.

Graphene OS is fine. Some months of delay are not a big deal.

I honestly suspect the country is Ukraine, money talks in Ukraine, find a contact there, you would be surprised, perhaps you save a life and rescue your developer.