First to market, but with beginner mistakes. I'll wait for a more mature EV truck myself. I want a simple box frame, with a body on frame, nothing fancy. Just pure utilitarian EV truck like a base F150 but with a battery.
I'm in the same boat with you. I want a truck or SUV to replace my 2003 LX470 (Land Cruiser) but aside from the body on frame construction, I really need a 500 mile battery. The 320 mile EPA extended range lightning loses about 64 miles of range from the recommended battery boundaries (don't charge above 90% or below 10%) and probably at least another 10%-20% loss from the high torque required offroading and the fact you'd probably never use regenerative braking since there's a lot more technique involved leaves you with about 200 miles of actual range. Throw on a roof top tent and some camping gear in the back and you probably have less and you have to account for the lack of jerry cans that can help you in a pinch if your planned mileage is increased from a bridge that's out or closed trail. I really want an electric SUV or truck to replace my main rig but some of the locations I go to are just too dangerous to run out of juice with. I think in about 5 years a dream rig of mine will be on the horizon
I've heard that EV trucks are mostly unibodies given the structure they need to protect and support the battery underneath. But I think the F-150 lightning is simple body on frame (as you said, although I think you are confused that this doesn't exist yet?), and the new Silverado EV will be neither unibody nor body on frame, whatever that means.
Unibody and body on frame have different pros and cons. Most people buying a truck want a unibody. The F150 lightening is only available in the crew cab version - you can get cars with as much cargo space. If you are actually hauling heavy things, or towing a trailer then a frame is strong and better able to handle that. However if you are only hauling people with some light luggage then a unibody is plenty strong and betters resists twisting forces making for a nicer ride.
I think F-150 Lightning is the closest to what you are looking for. But it has its own type of beginner's mistakes with the batteries. The charge curve isn't great, if that matters to you.
I wanted a B2 bollinger, and still love the concept. As a work truck, this has some features that would save me hassle. Also like the simplicity. But last I checked the cost was over 100k, which blew me away.