They are discontinued, but you can still find them on ebay and whatnot.

I don't know about the g5 specifically, I'd assume that's just a fancy way of saying it's got good motion detection. AI gets thrown around to attract attention

I have a g3 camera and it doesn't require an internet connection after the initial setup if you create a local login for the NVR, but it does still require a Ubiquiti hardware NVR (the cloud key g2 and some of the routers also work), which could be a turn off for most people