I can't find an app for Wallet on my iPad. What's the deal?

There is no Wallet app on an iPad. See the following from Wallet - Apple

The Wallet app lives right on your iPhone. It’s where you securely keep your credit and debit cards, driver’s license or state ID, transit cards, event tickets, keys, and more — all in one place. And it all works with iPhone or Apple Watch, so you can take less with you but always bring more.

There is an option to add cards to an iPad in Settings > Wallet & Apple Pay.