Board to Board Connections in Potted Electronics
Solder wires

There is little evidence that soldered wires are any more "time consuming or error prone" in potted PCBA at the scale of just 10 connections. 

The traditional causes of failure with unterminated wire connections are mechanical in nature and resolved by the additional stability that potting applies. In fact, most connector systems (including USB) feature similar construction inside their cable assemblies (connector -> miniature PCB -> wires -> mini-PCB -> connector)

Here, the overmolding of the cable is performing the same job that the potting will in your PCBA