Luckily with balloons, if you're just going for "somewhere over there" and you have reliable currents at steady elevations then you don't need to worry much about that. So yes the hardware and telemetry is mature.

Accurate navigation of such balloons however was never viable, which is why Alphabet shut down Loon two years ago. Navigation is achieved by inflating and deflating the balloon to rise or lower to catch favorable winds. But the navigational planning algorithms were never good enough.