Does anybody know whether the Bluetooth chip on the RockPi 4 supports Bluetooth Low Energy (BLE)? Is there driver support in, say, Ubuntu or Debian?
Yes, it supports BLE. I’m using BlueZ V5.50 and it works (almost) fine.
To Install BlueZ 5.50 follow this guide: https://scribles.net/updating-bluez-on-raspberry-pi-from-5-43-to-5-50/