I’ll do you one better. Sun rises at 6:30am for all time zones. Vast majority of clocks are digital now and can simply autocorrect at 3am each time zone.

This is the rarely-expressed exact opposite of DST abolition: literally do micro-DST every single day to keep local time adjusted to sunrise (though I would just do sunrise = 0:00). I actually... kinda respect it?

Some precedent in ancient chinese timekeeping:

This gets tricky because sunrise is impacted greatly by altitude and horizon obstacles. Better to set noon to solar noon/zenith all the time