I haven’t done it, but if EV Trip Planner says so, you should be good to go! IIRC there is an elevation drop which should help, also, you can *always* just drive a bit slower, and you’ll still save time over going through Ellensburg that’s for sure.
I did that route in 2012 in my Leaf (not all in one charge, but there are Chademo's every 50 mi). I was full in Leavenworth and had 9 mi on the Guess-o-meter with half a battery (out of 24 KWh) at the top of the Pass. I then coasted down to Skykomish and had ~40 mi on the GOM. You will be fine. Remember it's a 2-lane mountain pass and not a freeway, so speeds over 40 mph will be difficult at times.
Did the trip with no problem. Started in Leavenworth with 235 rated miles, and arrived at Centralia with about 50 rated miles. My first few road trips I used to strive to keep my "reserve" at over 20%. But I"m know comfortable at 15%, providing conditions are normal.