[baybal2]

On Android, JPG decoder lib may or may not use a DSP on Qualcomm SoCs, WebP doesn't have any hardware decoding support.

Any size gains will be much more noticeable in the context of network transmission.

[chrisandchris]

Which comes back to people having good phones most probably will have better internet and people habing cheap phones will have less good internet.

So you‘ll lose time either on transfer or decoding.