Love the idea, thanks for sharing!
One obvious concern here is data privacy, since the pass details are sent to the server. Any chance it would be possible to run everything in the browser, without sending data back to the server?
not really. the .pkpass needs to be signed. you can build the file locally but you won't be able to load it in apple wallet.
not really. the .pkpass needs to be signed. you can build the file locally but you won't be able to load it in apple wallet.