Regarding the Emergency Alert System:
Cell phones will work during power outages. First the cells towers use battery backup for upto four hours then in critical areas they can switch to backup generators.
https://www.techwalla.com/articles/do-cell-phones-work-in-power-outages
But the EAS (Emergency Alert System is not just text messages on cell phones. It includes: radio and television broadcasters, cable systems, satellite radio and television providers, and wireline video providers.
So for prolonged Electrical failure longer than a day, keep your radios active for EAS messages.
https://www.fcc.gov/emergency-alert-system