As I have now completed my 2nd coast-to-coast trip in my 2020 MYLR, anyone stating you can't EASILY do it, is spouting FUD.
NH->TX->Vancouver BC->NH, then later NH->BC->TX->NH Roughly 10,000 miles in an EV on each trip.
Also hit 17 National Parks along the way (bring my total up to 44 of 63), and completing geocaching in all 50 states (and now 7 provinces),
Extremely easy, just plug the day's destination into the navigation system and go. Almost zero range issues.
For full disclosure, I did stay at RV parks (slept in the back and got a full recharge (85%)) which made this much easier. There were a couple of spots where the RV park/recharge made the difference. Specifically, Glacier NP in Montana (after traveling via MN, SK and AB, Canada) and Zion->Bryce->Glen Canyon dam. Both spots are getting new SCs in the near future to solve those range issues.
I also used FSD Beta in both countries and it made the trip very pleasurable, most of the time, while occasionally giving me something to discuss with the car about its tendencies.
BTW, I recommend visiting BC in August/September and then visiting TX in October, and NOT TX in the summer and then BC.