Definitely don't let people edit it. iOS and Android don't allow picking your own MAC address for good reasons – people would inevitably pick 12:34:56, 00:00:00 etc. and cause problems for themselves and others.

To increase privacy, either randomize it (but make it much longer at the same time to avoid collisions) and/or remove it from as many signalling contexts as possible and keep it as a device-local identifier only (which then probably also doesn't have to be unique across manufacturers).