That deeply undercuts Rivian.
You wouldn't cross-shop a Rivian and a Slate. The Rivian is a high-end luxury vehicle with a laundry list of features, including things like self-driving. The Slate is literally the opposite: it has a laundry list of things it doesn't have and, indeed, its lack of features is part of the sales pitch.
Approximately zero people who are in the market for a Rivian would consider buying this.