I remembered to check https://pico.pinout.xyz/ for some hidden treasures in the advanced pin descriptions for PIN0 and PIN1 and I had completely forgotten the PWM functionality! 

With the help of this wonderful library https://github.com/khoih-prog/RP2040_PWM, I managed to get a speaker connected to GPIO0 and 1 in a pushpull configuration, meaning channel B is an inverted A. I remembered a CNLohr video where he used a pwm output with inverted channel of an attiny85 to basically amplify a microphone?