To be fair, if I was driving somewhere that was 200 miles between service and no cell phone signal, I don't think I'd do it with the factory doughnut spare on my 2014 either. Doughnut spares are only supposed to be used at 50 MPH max speed, for 50 miles max. 200 miles between service with no cell phone signal, to me, is approaching or crossed into the carry a full sized spare, plus a patch kit, plus an air compressor. I already carry an air compressor, and keep meaning to buy a good patch kit, and I'm usually never out of cell phone service nor more than 50 miles from a service center.
Also, this isn't new on the hybrid Siennas. On the 3rd gen Sienna (2011-2020), FWD models had a doughnut spare. But AWD models had no spare, and instead came with run-flat tires from the factory, which everybody says were terrible tires to drive on. There are a ton of threads on here with 3rd gen AWD owners looking to add a spare tire or showing how they added one, since they didn't want to replace run-flat tires with new run-flat tires.