This varies greatly by state and is evolving. Some general themes include granting an extension for license renewal, the ability for nurses to cross state borders to practice, waiving of restrictions imposed on advanced practice registered nurses (APRNs) and exemptions for inactive/retired nurses.
A comprehensive source to determine how you may be impacted can be found on The National Council of State Boards of Nursing’s (NCSBN) website.  The site is updated daily, Monday through Friday.