Most charging is done at home (YMMV), where prices range from 8 cents/kWh in Idaho to 18 cents/kWh in Connecticut and New York (a whopping 33 cents if you're lucky enough to live in Hawaii). This means it will cost $14.40 to refuel an empty 180 kWh Rivian battery in Idaho and $32.40 in Connecticut and New York, all to drive 400 miles. These are all theoretical numbers as few drive to a completely empty tank.
Yes, using the public fast charging (EVgo, Electrify America, etc.) will cost more. There is a recent Salt River Project (Phoenix area) EV study that showed EV drivers charged 81% at home, 16% at work, and 3% in public. Now we all can agree how a pickup truck or SUV driver may (or may not) drive differently than a Bolt or LEAF driver, and that people buy pickups and SUVs for capability and - if we're being honest - because they like them. I'm a huge Jeep guy, and the % that takes their Jeep off-road (low range) is barely at 10% last time I saw numbers.
For most customers, driving an electric truck or SUV will be significantly cheaper than the gas or diesel equivalent. That's even before you get to maintenance costs.