No, you didn't make calls on an Alexa powered device using Google Voice, and no, you can't.
As I said: the two companies are competitors. Their products do not inter-operate, period.
What you can do with Alexa devices is to make outbound calls that will spoof your mobile phone's caller ID. This is not using that carrier's network. It a VoIP call, where the ITSP is ... Amazon.
So, in theory, you can update your Amazon profile to set your own phone number to be your Google Voice number, and then calls from, for example, your Dot will show your GV CID. The calls are not going through Google's network at all.
You cannot receive inbound calls via an Amazon Alexa device.