-Xbox Codenames-
Xbox was actually the codename of the OG Xbox so that time the code name did carry over.
The 360 had several codenames. Xenon was the original launch hardware. Xepher was a refresh of the hardware with an HDMI port and a fix for the RROD. Then they called the next version Falcon, which was a further fix for the RROD. The Xbox 360 S was codenamed Valhalla. I'm mixed on Xepher and hate Falcon but Xenon and Valhalla are cooler than Xbox 360
I hate Natal which was the Kinect's code name, but Kinect isn't great either.
The original Xbox One was called Durango which sounds like a car not a game console, Xbox One is better but it's still a confusing name. I wish I knew what the Xbox One S's codename was.
Project Scorpio is awesome, but I think they should have just called it the Xbox in the final version.
-Nintendo codenames-
The NES and SNES are very Japanese businessie names. Family Computer and Super Family Computer.
Nintendo 64 started as Project Reality, but I kinda prefer the Ultra 64 codename/preliminary retail name over Nintendo 64 and Project Reality.
Gamecube was Dolphin, I prefer Gamecube
Remember when the tough, angry looking Reggie was talking about Project Revolution? Well that turned into the Wii and I still hate motion controllers in all it's forms. Revolution sounded amazingly cool.
Project Cafe for the Wii U, yeah not a great codename either.
NX, that was cool, Switch works fine but NX was cool.
-Sony codenames-
I'm not great on these codenames.
OG PlayStation was codenamed PSX and PSX later became a super high end version of the both the OG PlayStation and PS2.
PS4 was Orbis and I kinda like that over PS4, I'm not really a fan of incremental numbers for console names any more than I'm a fan of it for PC parts.