The reason why only the G3 supports Apple Wallet is exactly because of the NFC chip. Otherwise, they are completely the same hardware, and mostly the same software.
Thing is, the PN7160 chip used in G2 does not support Apple's proprietary extension to the NFC standard, called Apple Enhanced Contactless Polling [1], so they had to replace it with the PN7161 version, which is a special SKU created by NXP in collaboration with Apple. ECP modifies the lower levels of the NFC stack, which "NFC Controller" chips do not always give the host full control over, as they abstract away the protocol implementation for use in non realtime systems. Hence the need to replace the chip.
Funnily enough, PN7160 and PN7161 is exactly the same hardware with exactly the same firmware. NXP just 'fused' some extra data into *1 model so that it does not ignore the special configuration command to enable ECP. The extra SKU exists only because of licensing, and could have been a firmware update instead.
Theoretically, as ECP is really only needed for the automatic selection & use of a card, and it does not affect the upper protocol layers, UI could have brought support for Wallet credentials to older readers, just without the "express mode", but Apple specifically prohibits the use of their cards with any non-certified and non-ecp readers.
Thing is, the PN7160 chip used in G2 does not support Apple's proprietary extension to the NFC standard, called Apple Enhanced Contactless Polling [1], so they had to replace it with the PN7161 version, which is a special SKU created by NXP in collaboration with Apple. ECP modifies the lower levels of the NFC stack, which "NFC Controller" chips do not always give the host full control over, as they abstract away the protocol implementation for use in non realtime systems. Hence the need to replace the chip.
Funnily enough, PN7160 and PN7161 is exactly the same hardware with exactly the same firmware. NXP just 'fused' some extra data into *1 model so that it does not ignore the special configuration command to enable ECP. The extra SKU exists only because of licensing, and could have been a firmware update instead.
Theoretically, as ECP is really only needed for the automatic selection & use of a card, and it does not affect the upper protocol layers, UI could have brought support for Wallet credentials to older readers, just without the "express mode", but Apple specifically prohibits the use of their cards with any non-certified and non-ecp readers.
[1] https://github.com/kormax/apple-enhanced-contactless-polling