Do any Taiwan phone companies allow you to have one phone number over multiple devices?
For example your one phone number could be on your phone and your smartwatch and you can leave your phone at home. Or you could have multiple phones with the same phone number, one for daytime, and one for the beach that is waterproof or maybe an older phone that you want to have the same phone number but use to go hiking or something.
Samsung and T-Mobile in the USA have this capability called Digits. Samsung S6 and above have the capability.