Yup. Snapped an Ultegra chain at a thousand km. Later switched to KMC for ebikes which lasted a few thousand until worn without catastrophic failure. I ride the same model chains till present day even though I no longer use a mid drive. They're just so durable..

It was made by a guy in the US on his CNC. The build thread is still around. He made a mid-drive out of a light, high-RPM RC airplane motor and controller with a cycloidal gearbox to reduce it down 40x and then some more via the chain drive. This thing would do equivalent torque at the crankset of putting your body weight on the cranks, but it would do it continuously without overheating. All that in about 3kg. He made some tens/hundreds of these for a few years until he got a stable job at some corpo and no longer had the time for it. It was a crazy machine. Still have the drive stashed somewhere but I no longer use it. Some day I might build a simple fat bike with it for snow shredding. :D

Watch another guy climb a mountain at 30kph. That's the 6kW version limited to 4kW. The noise comes from the cycloidal gearbox, due to general vibration and not-so-great tolerances. They were significantly quieter after a few hundred kilometres.