My wife and I just did this trip a few days ago (Anaheim - Denver, with stops at Zion National, Bryce Canyon, Arches, and Grand Canyon/Parashant Monument). It was extremely smooth. The worst thing we had to do was back track after Zion. There’s a supercharger in St. George, UT that we stopped at before going to Zion, then we back tracked back to that same Supercharger at St George before heading to the next supercharger on route 15 in Beaver, UT and Bryce Canyon. A little note that we didn’t see on PlugShare is that Zion Visitors Center has a couple EV Charging Stations in the parking lot, and if we known that we may have been able to charge at Zion Visitors Center and go straight to Beaver Supercharger instead of backtracking... but that’s okay. We didn’t mind the extra 45 min or whatever it was after a long day of hiking. We enjoyed sitting in the A/C.
As far as the Northern Trim of Grand Canyon, I’m assuming you’re talking about the Grand Canyon/Parashant National Monument side. Going from St George, UT supercharger to there takes you on a 20+ mile dirt road. It’ll take an hour plus to get there, but you’ll certainly have enough battery for the trip. Just be careful with the car! It’s a really cool dirt road and it’s empty and beautiful, but certainly not the best for the suspension.
Good luck. You’re gonna love the trip.