Even without the diversion, it's actually slightly faster to go through Bend, OR when traveling Alturas, CA to Kennewick, WA than it is to stay on US395. Maybe it's a wash in a Tesla due to being less miles, I suppose. That stretch from Burns up to Pendleton looks like a bear. I've actually never done it!
If you are looking at routes going North and are considering going up to John Day and then East to the Baker City Supercharger, which is a shorter segment, I will give a caution about that one. That last part of the route on highway 7 through the mountains has a lot of tight switchbacks without warning signs, so it's kind of dangerous to do at night, with short visibility. I would only recommend that one in the day.The ride from Burns to at least John Day is really beautiful! I also think the next stretch is as well but cannot verify from personal experience!