The one thing I hope Apple has added to the pass framework is the ability to semantically define a barcode area.
This would enable them to finally have Wallet show ONLY that rectangle at a suddenly blinding brightness level (on HDR displays) for the scanner, rather than cranking up the entire screen.
That's not the only thing
Someone else mentioned TOTP codes that are hard to copy
My personal gripe is that NFC readers can't read wallet passes. That's also true for google/android.
Both apple/google restrict it and only few very big retailers are using it.
My wishlist item is support for TOTP in a code.
Some applications do want a code that's slightly less trivial to yoink than "look at a screen once, have it forever". TOTP would raise the bar there.
Every time I get blinded by this I wonder if it's really necessary at all...I can turn the brightness up myself if the QR code doesn't scan.