Tried to order through Apple, had multiple issues from them trying to charge me in full for a carrier financed phone to saying I couldn't check out because they required me to choose a payment card but the actual payment would be on carrier financing.
Switched to T-Mobile, app was a total bust. Tried on the website using my phone, got all the way to the last page of checkout, and the buy button was grayed out.
Finally got it to work on my desktop browser, 256gb white pro max. I realize these pre-orders put a huge strain on these systems, but there needs to be a better way. I spent an hour on a purchase that should have taken 10 minutes tops.