HI @fujiyama you are actually correct about the non-Canadian phone.
According to https://www.cwta.ca/for-consumers/wpa-sasfp/
There are many factors that will determine whether you will receive an emergency alert..
... Devices purchased from other countries are not certified by Canadian wireless service providers.
@shiqing843 is your phone a Canadian or North American version?
We actually don't want alerts on the Xiaomi so that worked out perfectly 😎
But I asked a friend who has an Oppo which has been flashed with android GSI (think of it like a rom that makes the phone almost "stock" android). It can get alerts but not reliably and received alerts are not always real-time...lol
So I'm not sure if you're willing to try flashing your phone just for the alerts. You can try asking on the XDA Vivo forums to see if they know other ways to enable alerts.
Oh and btw, neither phones are rooted. Our Xiamoi is stock, running on MIUI.
Go to settings and navigate to notification scroll down at the bottom and it will say govt. alerts and notifications you can click enable.
At lesast in Canada, those settings don't make a difference as these alerts will come in regardless of any of those alert settings.