How long do you think it took All Might to get to Osaka in the recent Vigilante chapter? Mirko stepped out, told the cops to make a call before stepping back in. Nighteye received the call, told All Might then he left.
The fight between O'clock, Rappa and Hood was still ongoing when Mirko busted right back in and ruined AFO's 3 seconds plan. So All Might arrived there in the time it took for Mirko to return to the battle after telling the cops make the call.
Eitherway, Tokyo to Osaka on a straight path without following official roads, since All Might flies is, 246.42 mi (396.57 km). In meters that's, 396,570 meters. Unfortunately the time is an assumption here but I don't think it could be more than a minute cause Mirko is pretty fast herself.
If it's 10 seconds, that would be 39,657m/s almost 40,000m/s which is Mach 116.
If it's 30 seconds ->13,219 m/s
But I think it should be less time not more.
It's only if one lowballs Mirko to need an entire minute to run back into the fight that All Might would get cut down to High-Hypersonic but if it's less than that then he's beyond High-Hypersonic.
Also I remember looking up how fast a nuke could launch a projectile and apparently one of the early nukes launched a cap at 60,000 m/s so if someone has the super-strength to basically output several hundred kilotons or megatons if power, you can basically guess their raw movement speed if launched with power like All Might's pseudo-flight would be around those speeds.