Can the medical insurance card be used nationwide? Can it be used in the province?

I can't.

At present, the medical insurance card can not be used nationwide, so the use of medical insurance card is still limited to the insured place. However, if you seek medical treatment in a different place, you can go through the registration formalities in the insured place first, and then seek medical treatment in a different place, then the medical insurance expenses incurred in the registered hospital can be settled directly with the medical insurance card without going back and forth.