Release Roku wireless speakers / subwoofer in Europe.
The US ones don't have multivoltage power supplies so can't easily be used if imported from US (short of using a building site step down transformer...large yellow ugly expensive thing).
If unsure of demand, then do something like a kickstarter to solicit demand, or offer a home theatre adapter instead (wireless connection, outputs 5.1 or similar to allow connection to external audio).
Oh and make the speakers wall-mountable with a standard small Vesa bracket or similar.
Not a Roku employee