Clocks on our ovens and some microwaves got out of sync during that period. I haven't seen any other device rely on the network frequency for timekeeping - everything time sensitive is already on NTP and GPS time.
The microwaves and ovens I've seen do not actually require you to set the clock. None of their cooking features and functionality depends on it. It's just a convenience feature. I doubt that most people actually need two clocks in the kitchen, so why not just set one of them (or neither if you don't need a kitchen clock at all)?
I guess I've been lucky in that all the microwaves I've had over the last couple of decades, and the ones we had at work, do not show the time unless you've set it. My current one, which has 7 segment LEDs for the time digits, blanks all the digits, leaving just the colons. My prior one showed "--:--" if time was not set. The one before that had a graphical display and just showed blank where the time would normally go.
Depending on where I am I see one of them so all must be synchronized to the millisecond so that children are not late to school (school is nearby, which exponentially raises the risk of them being late because it is just "4 minutes" away).
This is one of the scientific uses of such multiple clocks.
It's an old Bosch HBN202S
On top of that it had a dedicated button for toggling between AM and PM when setting the clock, which served no purpose whatsoever after that point. I wish I knew what the designer was thinking when they came up with that.