I just picked up the WeChip G20 which is the perfect controller however much to my dismay I found out only the Power button has the learning function.
Are there any remotes that meet these requirements?
Must Have
Nice to have
Rii mx6 v2 should meet your requirements
The Alexa Voice Remote (2nd Gen) is excellent other than the fact that the voice function doesn't currently work with the Shield TV.
Voice functionality for the 2nd gen Alexa Remote has been added to current test release firmware which means it should work after the next stable firmware release.
If you aren't asking for use with a Shield TV then this remote may not be the answer you're looking for.
look for Remote G30 that have function of 33 ir learning keys..has two versions one with two IR keys and 33 IR key learning keys
What do you mean by "CEC for Power/Volume"?
CEC is HDMI-CEC . This is the ability for devices to control each other (Shield<->Receiver<->TV, etc). For examples: turning off my shield turns off the TV, volume up on the remote tells the Shield (through Bluetooth/RF/IR) to tell the TV to turn up the volume (through CEC).
CEC does not apply to a remote. When you say CEC, do you mean programmable? In that case, you're probably looking at a fully programmable remote like a Logitech Harmony or something like a FLIRC to control the Shield with a remote that can control the TV/Receiver too.