Microsoft Store purchase/order issues in the U.S., Microsoft currently lists:
1-800-642-7676
Microsoft Sales Support, available Monday–Friday, 6 AM–6 PM Pacific Time.
Microsoft's own order-tracking page says that when an order is still Processing, it hasn't shipped yet, and tracking generally appears after shipment.
However, what you are describing is a little more concerning because:
Delivery is supposedly tomorrow
Order still says Pending
You can see the credit card/payment method
You have not received an alert about payment failure
You have not received an address/verification problem
You have the order number
That doesn't automatically mean something is wrong, but with delivery scheduled for tomorrow, I would absolutely have Microsoft check the order internally.