I can also follow up and say that yes, they can be disabled.
GrapheneOS Foundation is based in Canada where every alert is Presidential and cannot be disabled to my knowledge. This became so much of an issue for them they allowed you to force disable it.
Wireless alerts are fully optional since GrapheneOS adds a toggle for the otherwise mandatory presidential alert type. This is particularly useful in Canada where the government abuses the system and sends every type of alert as a presidential alert to stop users from being able to opt out of weather and amber alerts.
No way ! This is awesome.