iPhone since 8th gen has had NFC-F / FeliCa support:
This is must have feature in Japan, and in other metro areas in SE Asia and US that have adopted it for transit.
I’m sure open source HW advocates will advocate against inclusion of any such HW, but I thought I’d suggest it anyways because it is a deal breaker in adoption in some regions
I could definitely see the sense in stuff like extra battery pack add-on. Yes, the L5 would get crazy thick, but it would be a choice of the user.
And under the same logic there could be a FeliCa add-on case.