I found information about saving tickets in Google Wallet.

Hi,
We were talking recently about this in thread "Save tickets in an emmail?".
I chanced into a link that explains all this, while talking about a new feature in Google Wallet. It is in Spanish, but perhaps someone can find it in English. Or use Google Translate:
Original:
https://www.xatakandroid.com/aplicaciones-android/puedes-abrir-archivos-pkpass-google-wallet
Translated:
https://www-xatakandroid-com.translate.goog/aplicaciones-android/puedes-abrir-archivos-pkpass-google-wallet?_x_tr_sl=auto&_x_tr_tl=en&_x_tr_hl=en&_x_tr_pto=wapp
     You can now open PKPASS files with Google Wallet
     Google agrees to one of the main requests of Google Wallet users:
     to be able to import PKPASS passes from Apple
I'll summarize.
Apparently there is a (proprietary?) file format from Apple, called "PKPASS". There are apps to open them in Android (I use "PassWallet"). The file can come simply attached to an email. It is used for all kind of tickets, boarding passes, covid passports...
    «A PKPASS file is nothing more than a ZIP with everything
     necessary to generate the ticket or loyalty card (images,
     JSON files and so on). It is a standard created by Apple
     and not an open standard, although over time it has become
     a de facto standard, as there simply were not many other
     ways to do the same thing.»
The equivalent in the Android world is Google wallet, and it is not a file but an API. You have to click on a link somewhere.
    «Google chose a different route with Google Wallet .
     Google Wallet   Passes are not files, but developers
     must use the appropriate API and are offered to users
     as a link (usually with the Add to Google Wallet button)
     that can be embedded in a website, application, email,
     SMS or similar. It's just more complicated than necessary,
     so many services still offer to create a PKPASS file
     with our loyalty/boarding/other card, but not a link
     to add to Google Wallet.»
And Google is now adding to Wallet the ability to read .pkpass files.
I seem to understand that Wallet stores them in "the cloud" somewhere.
--
Cheers, Carlos.