Is the Sleep A20 good for side sleepers?

Yes. The shell is smaller than the A10 and sits flat enough that most side sleepers feel little pressure. Fit still depends on using the smallest tip that seals.

Does it block snoring?

Only partly. There is no active noise cancellation, so it masks steady sounds like fans or traffic better than sharp ones like snoring. Loud snoring will still get through.

Can I use it for music and calls?

It streams Bluetooth audio, but sound is tuned for sleep and masking. Music sounds flat and there is no call microphone quality worth relying on.

What is the charging case for?

It stores and recharges the buds, and it can act as a Bluetooth transmitter so you can hear a plane's seatback audio or a TV without pairing to your phone.

How does it compare with the A10?

The A20 is smaller, adds the transmitter case, sleep tracking and find-my-buds, and has longer battery life. The A10 is the cheaper option if you only want masking.

The app sets up masking sounds, sleep tracking, alarms and firmware. The buds play their built-in sounds without a phone, but you need the app to change settings.