The UK system has "severe alerts", which is what the wildfire alert was, and "extreme alerts" which is a higher category. Both trigger the siren sound, but sending this in the second-highest category seems ok to me.
Both levels can be deactivated on Android (no idea about iOS but I presume it's the same), there's no unblockable presidential alert level.
Both levels can be deactivated on Android (no idea about iOS but I presume it's the same), there's no unblockable presidential alert level.