For the sound, as indicated in the "details" section, I use the Adafruit "MAX98357 I2S Amp Breakout board" and a Gameboy SP speaker. It's a digital to analog decoder and also an amplifier and allows to directly connect a mini speaker.

The amplifier can deliver up to 3W depending on the impedance of the loudspeaker, the power supply used and the tolerated distortion. It can be supplied with a voltage between 2.7 and 5.5V.