The default configuration of KDE Neon does not work with the headphones. I have managed to connect them doing some changes, and adjusting some configurations. This resumes that, to keep it if I need to reconfigure them in the future.
This configuration has worked for me using the following setup:
- KDE Neon 5.20, kernel 5.4.0
- Freebuds Pro version 1.9.0.256