Hmm .....
This might be possible. Look into installing Echo Speaks. I don't use it, but I know it is possible to control some Alexa-paired devices using it.
Edit:
Also, if Blink can be controlled using an Alexa Routine then you don't need Echo Speaks. You can simply have the routine triggered by the state of a Hubitat virtual contact or motion sensor that is exposed to Alexa.