> something like a Rivian but with Waymo tech

So a Tesla?

I bought a 2018 Model 3 that was later upgrade with HW3. I paid about $10K extra for the full auto-pilot. Elon back then said that eventually the car will come pick me up from the airport. That was a nice dream. Nearly 10 years later, my Tesla still cannot do that.

$10K for full autopilot on Tesla in 2018 was essentially a fraud. I have since then learned not to trust anything Elon says.

Off-roading aspirations and 3rd row legroom (S1) seem to be major differentiators from Rivian.

As for autonomy, Waymos have LIDARs which at least provides more redundancy.

I see these as different design tradeoffs so no judgment implied.

I, independently, made almost exactly the same comment before seeing yours lol. I already do 20+ hour cross-country trips in my Y without a break to sleep, which is only possible because I'm not meaningfully fatigued driving. it's still technically supervised but I think that's beyond the point OP is making