zzz uses a trigger-style mouse to play distinctive sounds. Wear it during sleep and test your reality in dreams by squeezing your finger or thumb. If you hear the sounds, you can recognize that you're asleep and take control of the dream.
Depending on your Pi OS version you may need to add --break-system-packages here; this is fine if your Pi will be a dedicated zzz machine and you don't care about your Python environment; otherwise, create a virtual environment.