I’m thinking using a Raspberry Pi zero instead of a Rasbperry Pi A+.
Pi Zero runs at more Mhz and I think it uses less energy which means more battery.
I would like to add a jack for audio to use headphone instead Pocket PiGGRL amplifier and speaker (I expect better sound quality and something not disturbing other passenger in public transport).
Adafruit already done that for the Pi Zero and is documented here.
An USB wifi dongle is needed during installation part. You won’t need it afterward.