Set up OMNY

I guess he is asking about the OMNY card. Currently, Feb 2023 you can't add your OMNY travel card 'that you buy in a store to your apple wallet like the Hongkong Octopus, Japan Pasmo & Washington D.C Smartrip travel cards. Hopefully, Apple can come to an agreement with OMNY to integrate the OMNY physical card into the apple wallet in a similar way to those travel cards I just mentioned. OMNY only allows apple pay via debit & credit card payments using debit & credit cards stored in your apple wallet

See the information at https://omny.info/ including the following:

Coming soon to Android and iOS: the OMNY mobile app

There is a Google Pay app for iPhone but I haven't used it. I suspect that it would be better to use Apple Pay. See: Set up Apple Pay - Apple Support

and

https://omny.info/about-contactless-payments#what-are-digital-wallets

You add your digital card to your Apple Wallet. No additional app is required.

https://omny.info/about-contactless-payments#what-are-digital-wallets