Unique ID for Apple Passes?

I'm trying to implement a unique Id for each pass that someone adds to their wallet. Something like a unique membership Id or even something as simple as displaying a unique username. What is the process of setting this up?

I already have everything set up to generate the pass and update the values of the pass fields, but how can I make this specific to a single pass? I feel like I have everything I need to support this but not sure of the workflow I should use.

I found this endpoint: https://developer.apple.com/documentation/walletpasses/return_a_personalized_pass but unsure what the personalizationToken is or how I'd provide this. Is this the same as the "pushToken"?

It also references this: https://developer.apple.com/documentation/walletpasses/personalizationdictionary/requiredpersonalizationinfo which seems to require previously entered user information.

Unique ID for Apple Passes?
 
 
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