At CES 2020 someone took a photo of Rivian's home charger and the thing that stands out is the "Installed by Amazon home services" written on the display.
On Amazon's website it says "All our service pros are handpicked and required to be business background-checked, insured, and licensed if applicable" so it does seem like it has to be Amazon approved.As a former Amazon employee, my understanding is that Amazon Home Services would only approve a licensed electrician, but yes, you can always contract your own professional. I'm sure we'll know more as we get closer to delivery.
I ordered a Chargepoint Home Flex using the same email address as my Rivian pre-order. My Chargepoint app automatically added a “Subscribers - Rivian Auto Integration” entry under my Connections menu setting.That charger in the picture appears to be a ChargePoint Flex. It's even got ChargePoint branding on it. Nothing to indicate it's special to Rivian.
Amazon outsources installs to local contractors of the "lowest bid" variety. No way would I use them. If you aren't comfortable installing the charger, yourself, then find a quality electrician.