At what granularity? Using a theoretical horizon, or the actual local horizon even for valleys? Most days aren't the equinox, so how would this deal with seconds being fixed but the 12 daytime hours being a different amount of actual time from the 12 nighttime hours? Would a kWh be a different amount of energy depending on what the date is and whether it's daytime or nighttime?

If I ever become a crazy dictator, I will implement this idea.

Then your 7am will almost NEVER match my 7am. Or anyone else's 7am. It may only be by nanoseconds, or it may be hours (i.e. east coast vs west coast USA). So how would that even work in the real world?

What, so a second’s length changes? Or there is a variable and non-integer number of hours in a day? Or minutes in an hour?

hope you don't live near of the earth poles.