I've made a request for user research on where people would expect to find this -- in "About this phone", in "Phone" settings, in "Cellular" settings, in the Contacts app, or somewhere else.
That shouldn't stop anyone from implementing it: being in any of those places would be better than none at all. Remember that the presentation would need to differ for single SIM vs. dual SIM: in single SIM it could be a single “Phone number" item, whereas in dual SIM it would be a "Phone number:" section with items for each SIM.
I've made a request for user research on where people would expect to find this -- in "About this phone", in "Phone" settings, in "Cellular" settings, in the Contacts app, or somewhere else.
That shouldn't stop anyone from implementing it: being in any of those places would be better than none at all. Remember that the presentation would need to differ for single SIM vs. dual SIM: in single SIM it could be a single “Phone number" item, whereas in dual SIM it would be a "Phone number:" section with items for each SIM.