Problem: I bought a new wireless Logitech Pebble Keys 2 K380s Keyboard but it refused to connect to the PC. Unfortunately, I do not (yet) own a Logitech Bolt, so I wanted / needed to connect via Bluetooth. With the Phone it was able to connect.
Cause: My Bluetooth Dongle is a Sitecom CN-516 with Bluetooth 2.1, while the keyboard requires Bluetooth 4.
Solution: Get a Logitech Bolt Receiver (The Logitech Unifying receiver is not supported by the Pebble!) or a Bluetooth Dongle supporting at least Bluetooth 4. In 2024 all major dongles should be at least Bluetooth 5.0.
It might be a good idea to reset the Pebble Keys 2. This is done easily by hitting the following keys one after the other: ESC-o-Esc-o-Esc-b. After those 6 keystrokes, the 3 blue LEDs right next to the ESC button start flashing.