Noo, I literally faced some bug a week ago, when I wasn't able to install new eSIM, it was just hanging for a minute and that's it - no error and no esim installed. The only thing that saved me from resetting my phone - is previously booked physical sim card. Just put it in and it works.

Second concern is if you accidentally crash your phone during the travel. You have to pass two-factor authentication on new phone to sign in to your Google account and install software to download your eSIM. But how can you pass it without an eSIM?