That’s not even enough because different zones observe DST at different times, or not at all. You would have to enter your actual time zone, not an offset, like when you install an OS or something. And then if that zone ever changes, which happens a lot, the clock in your microwave will often, or always, be wrong. So now your microwave needs to be internet connected to download tz databases, and what are we even doing here.
Thankfully DCF77 transmits the legal time and date including pre-announcing of skips for the country it operates from: Germany.
And for logistical reasons, the time zone extends quite far beyond the country borders. Co-inciding with where you have truly good reception.
