Waitlist instead of add-to-cart for scarce products: a quota of places, customer registration and single-use invitation links for a priority purchase.

WordPress Waitlist Plugin for Lead Generation, Early Access Programs, Pre-Registrations, and Launch Notifications.

Run a drop on WordPress: a waitlist before you open, a countdown to the date, and prize games that hand out codes. Free plan, from droplark.com.

Sell products before they exist. Take pre-orders, hold the order until launch day, then release it automatically.