i have the same issue:

root@Omega-0417:~# opkg install pyOnionI2C
Unknown package 'pyOnionI2C'.
Collected errors:
opkg_install_cmd: Cannot install package pyOnionI2C.
root@Omega-0417:~# oupgrade
Device Firmware Version: 0.1.4 b330
Checking latest version online...
Repo Firmware Version: 0.1.4 b330
Comparing version numbers
Device firmware is up to date!

How to fix it? opkg update did not helped.