Yes, foot pedals work with Sonix, but you will need to install some software on your computer to make it work.
For Mac: https://www.orderedbytes.com/controllermate/xkeys/
For Windows: https://www.nch.com.au/footpedal/
Then, you will need to map the different sections of the foot pedal to Sonix keyboard shortcuts. To see this list, click on the "Shortcuts" button on the bottom left of the Sonix editor.