Easiest way to setup a wallet card distribution web service that can also send notifications?

Hi,

I’m testing out different possibilities for a client that wants to have a loyalty card service where users can register to download and install a wallet pass. This wallet pass should be able to receive push notifications.

I have found a library that can generate apple passes but I struggle to find a good direction with the notification / update service. I’m most comfortable with using PHP but any other easy solution is also welcome.

What would be a good way to start and test things out?

Thank you!