Answer by Jason Yeaman:
Onavo is a cellular data compression service. The concept behind it is a secure VPN connection to onavo servers that will compress your cellular data to mitigate overage charges on limited throughput data plans.
Because the premise of their service on mobile is the data compression solution to save throughput metrics, wifi support isn’t their niche. While the security component would work on wifi, it’s not a great candidate for data compression because it’s free, and it’s free….and free.
The downside to data compression is it makes images less visually appealing by degrading the quality. On a larger display this wouldn’t be the experience one would want. and most desktops don’t use a cellular data plan for connectivity.
Since the screen is smaller on mobile, the quality hit won’t be as apparent.