You can’t lose something that you’ve never had.
The Wallet App is unique to iPhone - due to hardware…
The iPhone Wallet uses NFC to wirelessly communicate with physical Point of Sale (PoS) terminals - NFC being the mechanism used by ApplePay (and Google’s Android equivalent) to securely exchange registered Credit Card details and authorise a payment.
The Apple Wallet App has dependency upon NFC hardware which is absent from all models of iPad. Consequently, the Wallet App is not available for iPad. Whilst perhaps a moot point, consider the practicalities of attempting to bring a specific area of an iPad (which may be sizeable) within close range of a PoS terminal!
Whilst iPad does not have a Wallet App per-se, iPad does have Wallet in iPad settings. Here you can register Credit Cards for ApplePay - but this is not intended for NFC. Instead, iPad is able to participate in remote e-commerce payments - such as a website.
I hope this explanation brings useful clarity as to the capabilities of both iPad and iPhone in context of ApplePay and Wallet.